We’ve seen lots of hacks about capturing weather images from the satellites whizzing over our heads, but this nicely written how-to from [Eric Sorensen] takes a different approach. Rather than capturing images from polar satellites that pass overhead a few times a day, this article looks at capturing images from GOES-17, a geostationary satellite that looks down on the Pacific Ocean. The fact that it is a geostationary satellite means that it captures the same view all the time, so you can capture awesome time-lapse videos of the weather.
The fact that GOES-17 is a geostationary satellite means that it is a bit more involved. While polar satellites that orbit at an altitude of 800km or so can be received with a random piece of wire, the 35,800 km altitude of geostationary satellites means that you need a better antenna. That doesn’t have to be that expensive, though: [Eric] used a $100 parabolic antenna and a $100 Airspy Mini SDR receiver connected to an Ubuntu laptop running some open source software to receive and decode the 1.7GHz signal of the satellite.
The other trick is to figure out where to point the dish. Because it is a geostationary satellite, this part has to be done carefully, as the parabolic antenna has only a small receiving angle. [Eric] designed a 3D-printed mount that fits onto a tripod for his antenna.
Capturing satellite weather images is a fascinating thing to do, and this adds another level of interest, as the images show the full disc of the earth. Capture a series over time, and you can see storms spin around and across the ocean, and see just how complicated they are.
This is an exciting day for me — we finally get to build some ham radio gear! To me, building gear is the big attraction of amateur radio as a hobby. Sure, it’s cool to buy a radio, even a cheap one, and be able to hit a repeater that you think is unreachable. Or on the other end of the money spectrum, using a Yaesu or Kenwood HF rig with a linear amp and big beam antenna to work someone in Antartica must be pretty cool, too. But neither of those feats require much in the way of electronics knowledge or skill, and at the end of the day, that’s why I got into amateur radio in the first place — to learn more about electronics.
To get my homebrewer’s feet wet, I chose perhaps the simplest of ham radio projects: dummy loads. Every ham eventually needs a dummy load, which is basically a circuit that looks like an antenna to a transmitter but dissipates the energy as heat instead of radiating it an appreciable distance. They allow operators to test gear and make adjustments while staying legal on emission. Al Williams covered the basics of dummy loads a few years back in case you need a little more background.
We’ll be building two dummy loads: a lower-power one specifically for my handy talkies (HTs) will be the subject of this article, while a bigger, oil-filled “cantenna” load for use with higher power transmitters will follow. Neither of my designs is original, of course; borrowing circuits from other hams is expected, after all. But I did put my own twist on each, and you should do the same thing. These builds are covered in depth on my Hackaday.io page, but join me below for the gist on a good one: the L’il Dummy.
As Al points out in the article linked above, a dummy load is just a resistive element that matches the characteristic impedance of the transmitter’s antenna connection. In almost every case, that’s going to be 50 ohms. The reason that the load needs to be as resistive as possible is that it needs to continue looking like a flat 50-ohm load no matter what frequency is applied to it. Any inductive or capacitive elements in the load will make it more reactive, changing the impedance as the input frequency changes. This could lead to RF power getting reflected back into the final amplifier transistors in the transmitter, possibly damaging them or destroying them altogether. Not what you’re looking for.
That means our resistive elements need to be as non-inductive as possible. But, they also need to be able to dissipate a lot of power. The HT dummy load, which I’ve dubbed L’il Dummy, needs to handle the 5 to perhaps 8 watts an HT can output. Trouble is, power resistors in that range are often wirewound, and a coil of wire will have too much inductance. We’ll need to be clever in sourcing components.
The circuit for L’il Dummy is hardly worth a schematic – it’s just an SMA jack with a 50-ohm resistor across the outer ground and the inner conductor. I chose to build the circuit on an RF Biscuit board. This is an open-source design that enables all kinds of handy little RF circuits — attenuators, filters, and as in this case, dummy loads. The resistive element I chose was a thick-film SMT device capable of dissipating 35 watts – way more than enough for this job. That and an edge-mount SMA jack should have been all I needed to make a working dummy load.
To my surprise, once I soldered the resistor to the RF Biscuit board, the dummy load was almost as good an antenna as the stock rubber ducky on my Baofeng HT. I was able to hit a local repeater through the dummy load without any issues. Clearly not a good design. To correct it, I put the whole thing into an enclosure made from 1″ copper pipe. Not cheap stuff, but not too bad, and I like the look of polished copper. Soldering the whole case together was a challenge that my big Weller soldering gun wasn’t up to, and trying to get everything heated up enough with a propane torch without overdoing the heat was a fun time.
Testing on a Budget
Now for the $50 question: does it work? I tested the resistance with a DMM and it comes out to just about 49 ohms, which is close enough in my book. But that’s DC resistance; what about impedance? I don’t have an antenna analyzer, so I trolled around and found a simple method for measuring impedance with only a function generator and an oscilloscope. My scope has a 20-MHz function generator built in, so I whipped up a quick test jig from a BNC jack and an SMA jack, connected in series through a leftover 1000-ohm resistor.
Applying a sine wave into the dummy load, measuring peak-to-peak voltages on each side of the resistance, and doing a little math is all that’s needed to characterize the impedance from 2.5 MHz to 20 MHz. The math is simple:
with V1 being the voltage across the input, V2 being the voltage across the output, and Rref being the actual value of the series resistance, which I measured at 998 Ohms.
And the results are pretty close to 50 Ohms, and flat across the tested band
V1 (V p-p)
V2 (V p-p)
I wish I could measure it at VHF and UHF frequencies, but that will have to wait until I get a function generator that goes up to 400 MHz or so. I doubt very much that a $50 budget would cover that, though.
I had intended to cover both L’il Dummy and its bigger, somewhat smarter brother in one article, but I still have some testing to do on Big Dummy. I’ll cover that next time, and after that we’ll move onto measuring the output of a cheap Chinese HT and perhaps building a filter to clean it up.
Na de succesvolle velddagen in Bellevaux is de VRZA Zuid-Limburg in 2018 verhuisd naar Dairomont, vlakbij Malmédy. Een uurtje rijden vanuit Maastricht ligt dit vakantiehuis bovenop een plateau met een prachtig uitzicht over de omgeving, zoals je op de foto kunt zien.
De velddag vindt in 2019 plaats vanaf donderdag 30 mei (Hemelvaartsdag) tot en met zondag 2 juni. Tijdens deze dagen zullen 8 leden van de VRZA hun kamp opslaan en met diverse antennes en transceivers proberen zoveel mogelijk verbindingen te maken en experimenten te doen.
Net als vorig jaar zullen er een aantal antennes worden opgesteld voor de gebruikelijke HF banden en natuurlijk 2m en 70cm. Op die laatste band staat ON0TB altijd standby op 439.0125 MHz. De repeater PI3ZLB is vanuit Dairomont waarschijnlijk niet bereikbaar…
Zo laat in mei de velddag houden betekent een grotere kans op mooi en warm weer (check het weerbericht hier), een grotere kans op condities en daar zal gebruik van worden gemaakt! Diverse transceivers (én receivers) staan bijna volcontinue te snorren. Kortom: genoeg activiteit op de radio!
De velddag is natuurlijk ook door anderen te bezoeken. Hou er wel rekening mee dat er voor de maaltijden niet is gerekend op mee-eters dus zorg zelf voor eigen eten, indien nodig. Er zijn supermarkten genoeg in de buurt voor ad-hoc voedselvoorzieningen. Voor de consumpties wordt een bijdrage gevraagd. Wil je langs komen? Van harte welkom! Meld je even in via de repeater van Botrange: 439.0125 MHz (shift -7.6MHz), die staat continu aan tijdens de velddag. Nog beter: meld je vooraf aan tijdens een van de clubavonden en spreek af wanneer je komt zodat er rekening met je kan worden gehouden.
Parkeren in de buurt is geen probleem maar hou er rekening mee dat dit huisje in een gewoon dorp ligt dus hou rekening met omwonenden. De locatie is gewoon met de auto of motor te bereiken, je hoeft nu eens niet door het bos!
So far in this series, we’ve covered the absolute basics of getting on the air as a radio amateur – getting licensed, and getting a transceiver. Both have been very low-cost exercises, at least in terms of wallet impact. Passing the test is only a matter of spending the time to study and perhaps shelling out a nominal fee, and a handy-talkie transceiver for the 2-meter and 70-centimeter ham bands can be had for well under $50. If you’re playing along at home, you haven’t really invested much yet.
The total won’t go up much this week, if at all. This time we’re going to talk about what to actually do with your new privileges. The first step for most Technician-class amateur radio operators is checking out the local repeaters, most of which are set up exactly for the bands that Techs have access to. We’ll cover what exactly repeaters are, what they’re used for, and how to go about keying up for the first time to talk to your fellow hams.
Could You Repeat That?
Time to face some cold, hard facts about amateur radio: that spiffy new Baofeng radio I recommended last time as a great starter radio is actually pretty lame. That fact has little to do with the mere $25 you spent on it, or $40 if you opted to upgrade the antenna. It’s a simple consequence of physics: a radio that transmits at 5 watts will only have so much range on the VHF band, and even less on UHF. Even if you buy a more powerful HT, or invest in a mobile or base-station rig running 50 or 100 watts, the plain fact is that direct radio-to-radio contacts on the same frequency, or simplex contacts, are difficult on VHF and UHF because those bands are really best for line of sight (LOS) use.
That’s not to say that hams don’t use their VHF and UHF rigs for simplex communications, of course. Many hams like to see just how far they can push their signals on these bands, building big Yagi antennas and finding mountain peaks to operate from. But for general use around town, most hams rely on repeaters to extend the area they can communicate over. Repeaters are simply transceivers set up to receive signals on one frequency and transmit them on another at the same time, with the help of a device called a duplexer. This simultaneous reception and transmission gives rise to the term duplex communications, the general term for operating on a repeater.
Repeater usually transmit at a much higher power than an HT or even a mobile rig can manage, and they usually have the advantage of being located on a mountaintop or some other elevated place to gain the furthest possible radio horizon as possible. This arrangement vastly increases the area that you can cover with your tiny HT. Depending on how the repeater is sited and what sort of antenna it has, you may be able to cover hundreds of square miles, as opposed to perhaps a few miles radius under ideal conditions, or a few blocks in the typical urban or suburban setting with lots of clutter from buildings and trees. What’s more, some repeaters are linked to other repeaters either through backhaul connections, often via the Internet but also sometimes through powerful LOS microwave links. In these systems it’s possible to use a puny HT to talk to another ham over hundreds or even thousands of miles. It’s actually pretty cool.
Welcome to the Machine
So where are these repeaters, and how do you start working them? The first question is easy to answer: they’re everywhere. Look at any tall building, mountaintop antenna farm, or municipal water tank, and chances are pretty good there’s a ham repeater there. But being able to work them means you need to know exactly where they are, to be sure you’re in range of the repeater, or “the machine” as hams often refer to it, as well as the frequencies it operates on.
Luckily, there are online guides to help with that chore. RepeaterBook.com is usually the first place hams go to find machines in the area. There you can search by state, county, or city, or even via a map, and find what repeaters are available. They’ve even got a handy road search, so you can get all the repeaters listed as within range of a particular highway; that’s really handy for road-trip planning. Here’s what comes up for VHF and UHF repeaters when I search within 25 miles of my location, or QTH:
The first thing you’ll notice is that several machines at different sites have the same callsign. For example, K7ID runs a UHF repeater on Canfield Mountain and a VHF machine on Mica Peak. Both are LOS to me, and I can easily hit them with an HT. The frequency listed in the first column is the transmit frequency of the repeater. Your HT will need to be set to this frequency to hear what’s being said. Your radio will also need to be programmed for the correct tone, listed in the third column. That tone is an audio frequency signal known by a number of different trade names, but generically as continuous tone-coded squelch system (CTCSS). Your radio is capable of adding this sub-audible tone to your transmission; the repeater will only “open up” to transmissions that are correctly coded. Some repeaters have no tone coding, others have different tones for receive and transmit. When doubt, try to find out who runs the machine – most, but not all, are run by a ham radio club – and see if you can look up instructions on the web.
The offset shown in the second column is perhaps the most important bit of information. Recall that repeaters transmit and receive on different frequencies, and that they’re listed by their transmit frequency. The offset tells you what the repeater’s input frequency is, which is the frequency your radio will need to be set to transmit on. For example, the machine I most often used is the K7ID machine on Mica Peak. It’s at 146.980 and shows an offset of -0.6 MHz. That means that my radio has to be set to 146.380 MHz transmission frequency. VHF repeaters are usually 0.6 MHz, but could be plus or minus depending on which part of the VHF band they’re in. UHF repeaters usually have +5 MHz offsets.
Note: I’m not going to cover programming your radio, because there are plenty of guides online that do a better job than I can. DuckDuckGo is your friend.
Casting the Net
Once you’ve found your local repeaters and programmed your radio, it’s time to get on the air. My advice is to spend the first few days just listening to one or more repeaters. Activity levels vary – some machines are hopping all day, and some are barely used except during the typical commuting hours. When you hear a conversation, try to get a feeling for the culture of the repeater. Every group of hams has a culture, and as we discussed in the first installment of the series, it’s not always a healthy culture. My local repeater belongs to the Kootenai Amateur Radio Society, as friendly and as inviting a group of people as I’ve ever heard on the air. After listening to them chat for a few weeks, I was more than ready to reach out to them.
But first, a word about kerchunking. If you want to know if you’re in range of a repeater, you can test it out. Most repeaters have a “squelch tail” that keeps the repeater on the air for several seconds before going back to sleep, and this can be used to check if you’re in range. Some repeaters even identify themselves, either with a synthesized voice or Morse code when they “wake up”. So you might want to ping the repeater.
Kerchunking, or transmitting into a repeater without identifying yourself, is one of those bad habits that everyone seems to have. But FCC part 97 rules, which cover the amateur radio service, require operators to transmit their call sign when they start a transmission. So don’t kerchunk; a simple identification like “This is KC1DJT testing and clear” will suffice. Nobody is likely to take that as an invitation to chat, but they might give you a reception report.
Once you’re feeling confident enough, try making a contact. I highly recommend checking out the local traffic networks. Hams pride themselves on having the skills and equipment to communicate in an emergency, but that means little without practice to keep everything sharp. Nets allow hams to practice message passing skills and to test their gear on a regular basis. My local group has a network check-in every night that follows a standard script and usually attracts about 30 check-ins. Here’s a sample from a recent check-in:
I’ve become a regular on this net and a few others, mainly because I want to practice, but also to get over my mic shyness. There’s another reason too – I want people to recognize my voice and callsign. If there ever is an emergency in my area, I feel like it’ll be easier to pitch in or to get help if I need it if people hear a familiar voice.
Over the next few installments, we’re finally going to get to what I think ham radio is all about at its core: homebrewing. We’ll be building a few simple projects to make that cheap HT a little better, and also build a few tools to help run the shack a little more efficiently.
Op 11 mei is het Nationale Molendag, een dag waarop je verschillende molens in Nederland kunt bezoeken en kunt zien hoe vroeger – en ook nu nog – molens werk verzetten.
De VRZA Zuid-Limburg is die dag aanwezig bij de Tienhovenmolen in Bemelen (klik voor details) om met het station PA6TIEN mee te doen aan Mills On The Air 2019. Daarbij zijn diverse stations in binnen- en buitenland actief op diverse banden om verbindingen te maken met elkaar en natuurlijk met radiozendamateurs over de hele wereld.
PA6TIEN zal actief zijn op 40m en 2m en natuurlijk ook op andere banden, afhankelijk van condities. Het station zal actief zijn tussen +/- 11:00 en 17:00 uur.
Tijdens het bezoek van de molen is er natuurlijk ook gelegenheid om te komen kijken bij het radiostation.
Tijdens de gezamenlijke lezing in februari is aangekondigd dat er in de week van 6 mei een oefening wordt gehouden in Zuid Limburg. Als zendamateurs zijn we benaderd met de vraag om op onze banden wat activiteit te maken die kan worden verwerkt in de oefening. Inmiddels begint het programma wat meer vorm te krijgen. De belangrijkste punten voor ons zijn:
Tussen maandag 6 mei circa 15 uur en dinsdag middag ca 15 uur:
afwisselend een aantal korte rondes en mini contest met
verschillende digitale modes, en op rustiger momenten baken
woensdag 7 mei test met reflectie van zendsignalen tegen
Wat heb je hiervoor nodig?
Een vaste, portable of mobiele locatie van waaruit je het gebied Maastricht – Margraten kan bereiken op VHF/UHF
Zendontvanger op 2m en/of 70 cm met bij voorkeur FM en SSB, plus interface voor digitale modes
PC met software voor digitale modes: FLdigi, WSJT-X (versie 2), MixW (versie 3).
De opzet is zodanig dat je voor kortere of langere tijd kan deelnemen, aan een of meerdere onderdelen.
Een deel van de informatie zal ook op de website a22.veron.nl worden gepubliceerd. Een ander deel met de details van de oefening is alleen bedoeld voor de deelnemers.
Wil je en kan je voor een deel of het geheel deelnemen, meldt je dan aan bij Tom PC5D@home.nl
Tube Time @TubeTimeUS
March 31, 2019
Take a look at these fascinating and educational cross sections
of an LED, resistor, diode, capacitor, and more. (The images in this
Moment created by TubeTimeUS are licensed under CC BY-SA 4.0:
here’s a cross section of an LED! it still works too.
LED cross section — now with annotations!
here’s a cross section of a resistor!
and here it is with labels on the important bits. you can see part of the spiral gouge left by the trimming equipment. during manufacture, this machine removes carbon film, increasing the resistance until it hits the target value.
compare that with this old-school carbon composition resistor. it’s just carbon powder inside a phenolic tube.
this carbon composition resistor has a value of 7.5 ohms. doesn’t take much carbon to get that resistance!
here’s the cross section of a diode! it’s a 1N4007. you can see the piece of silicon in the middle. the lumps on the wires help hold them in the plastic case.
here’s a cross section of a surface mount ceramic chip capacitor.
here’s the annotated version. i’ve drawn in lines over 4 of the capacitor plates near the bottom to make them a bit more clear.
cross section of a film capacitor.
cross section of a ceramic disc capacitor. you can see the ceramic disc right across the center.
check out this cross section of an inductor!
annotated version of the inductor cross section.
annotated cross section of a film capacitor.
cross section of an electrolytic capacitor! i’ll annotate it shortly.
adjusted the annotations to correct a mistake. the paper in between the layers of foil is not actually the dielectric! when soaked in electrolyte, it serves as the cathode (‘-‘ terminal). the dielectric is an oxide layer grown on the anode (‘+’ terminal).
top view cross section of an electrolytic capacitor.
Here’s a version with each plate colored in to make it easier to trace how they’re wrapped around each other.
here’s the cross section of a dipped tantalum capacitor.
annotated cross section.
cross section of a 15-turn potentiometer
close-up of the slider. this part moves left and right as you turn the adjustment screws.
annotated version of the 15-turn trimmer potentiometer cross section.
have a look at this cross section of a tact switch!
annotated diagram of a tact switch cross section. in the photo, the button is pushed down and the dome is shorting the center contact to the outside contacts. when you let go, the metal dome snaps up, making a tiny click and breaking the circuit.
ok this is the cross section of a 2N3904 NPN transistor. what’s that tiny little speck?
it’s the transistor silicon die! the little gold dollop on top is the emitter bond wire! the big metal slug underneath is the collector terminal.
annotated version of 2N3904 NPN transistor cross section.
here’s a cutaway view of a classic 12AX7 vacuum tube triode. discriminating musicians use these tubes in their guitar amplifiers — you’ve definitely heard the sound before!
this is the annotated cutaway diagram of the 12AX7 vacuum tube.
in the middle of this photo, you can see the coated filament wires entering the hollow cathode. the filament heats up the cathode. this produces an aura of electrons called the “space charge” region.
how about a closeup of the grid wires and the cathode? the white powder is oxides of barium, strontium, and calcium, which improves electron emission. the control grid, if biased negative, repels the electrons, caging them up. otherwise they pass through the grid to the plate.
here’s a cross section of an Ethernet transformer. inside a network adapter, there is one of these in between the Ethernet PHY chip and the cable, providing isolation and safety.
here’s the side view cross section of an Ethernet transformer.
annotated version of the Ethernet transformer cross section.
ok don’t try this one at home: this is a cross section of an LR44 alkaline button cell!
annotated cross section of the LR44 alkaline button cell.
There used to be a time when amateur radio was a fairly
static pursuit. There was a lot of fascination to be had with building
radios, but what you did with them remained constant year on year. Morse
code was sent by hand with a key, voice was on FM or SSB with a few
old-timers using AM, and you’d hear the warbling tones of RTTY traffic
generated by mechanical teletypes.
By contrast the radio amateur of today lives in a fast-paced world of
ever-evolving digital modes, in which much of the excitement comes in
pushing the boundaries of what is possible when a radio is connected to a
computer. A new contender in one part of the hobby has come our way
from [Guillaume, F4HDK], in the form of his NPR, or New Packet Radio mode.
NPR is intended to bring high bandwidth IP networking to radio
amateurs in the 70 cm band, and it does this rather cleverly with a
modem that contains a single-chip FSK transceiver intended for use in
licence-free ISM band applications. There is an Ethernet module and an
Mbed microcontroller board on a custom PCB, which when assembled
produces a few hundred milliwatts of RF that can be fed to an
off-the-shelf DMR power amplifier.
Each network is configured around a master node intended to use an
omnidirectional antenna, to which individual nodes connect.
Time-division multiplexing is enforced by the master so there should be
no collisions, and this coupled with the relatively wide radio bandwidth
of the ISM transceiver gives the system a high usable data bandwidth.
Whether or not the mode is taken up and becomes a success depends
upon the will of individual radio amateurs. But it does hold the
interesting feature of relying upon relatively inexpensive parts, so the
barrier to entry is lower than it might be otherwise. If you are
wondering where you might have seen [F4HDK] before, we’ve previously
brought you his FPGA computer.
There are a few options if you want to network computers on
amateur radio. There are WiFi hacks of sort, and of course there’s
always packet radio. New Packet Radio,
a project from [f4hdk] that’s now on hackaday.io, is unlike anything
we’ve seen before. It’s a modem that’s ready to go, uses standard 433
ISM band chips, should only cost $80 to build, and it supports
bidirectional IP traffic.
The introductory documentation for this project
(PDF) lays out the use case, protocol, and hardware for NPR. It’s based
on chips designed for the 433MHz ISM band, specifically the SI4463 ISM
band radio from Silicon Labs. Off the shelf amplifiers are used, and the
rest of the modem consists of an Mbed Nucleo and a Wiznet W5500
Ethernet module. There is one single modem type for masters and clients.
The network is designed so that a master serves as a bridge between Hamnet,
a high-speed mesh network that can connect to the wider Internet. This
master connects to up to seven clients simultaneously. Alternatively,
there is a point-to-point configuration that allows two clients to
connect to each other at about 200 kbps.
Being a 434 MHz device, this just isn’t going to fly in the US, but
the relevant chip will work with the 915 MHz ISM band. This is a great
solution to IP over radio, and like a number of popular amateur radio
projects, it started with the hardware hackers first.
In the radio business, getting the high ground is key to
covering as much territory from as few installations as possible.
Anything that has a high profile, from a big municipal water tank to a
roadside billboard to a remote hilltop, will likely be bristling with
antennas, and different services compete for the best spots to locate
their antennas. Amateur radio clubs will be there too, looking for space
to locate their repeaters, which allow hams to use low-power mobile and
handheld radios to make contact over a vastly greater range than they
Now some hams have claimed the highest of high ground for their
repeater: space. For the first time, an amateur radio repeater has gone
to space aboard a geosynchronous satellite, giving hams the ability to
link up over a third of the globe. It’s a huge development, and while it
takes some effort to use this new space-based radio, it’s a game
changer in the amateur radio community.
Friends in High Places
The new satellite, Es’hail-2,
was built for Es’hailSat, a Qatari telecommunications concern. As
satellites go, it’s a pretty standard machine, built primarily to
provide direct digital TV service to the Middle East and Africa. But
interestingly, it was designed from the start to carry an amateur radio
payload. The request for proposals
(RFP) that Es’hailSat sent to potential vendors in early 2014
specifically called for the inclusion of an amateur repeater, to be
developed jointly by AMSAT, the Radio Amateur Satellite Corporation.
The repeater aboard Es’hail-2 was developed as a joint effort between the Qatar Amateur Radio Society (QARS), Es’HailSat, and AMSAT-DL,
the AMSAT group in Germany. The willingness of Es’HailSat to include an
amateur radio payload on a commercial bird might be partially explained
by the fact that the QARS chairman is His Excellency Abdullah bin Hamad
Al Attiyah (A71AU), former Deputy Prime Minister of Qatar.
The repeater was engineered with two main services in mind. The first
is a narrowband transponder intended for phone (voice) contacts,
continuous wave (CW) for Morse contacts, and some of the narrow
bandwidth digital modes, like PSK-31. The other transponder is for
wideband use, intended to test Digital Amateur Television (DATV). The
wideband transponder can carry two simultaneous HD signals and a beacon
broadcasting video content from QARS. Both transponders uplink on the
portion of the 2.4-GHz reserved for hams, while downlinking on the
Es’hail-2 was launched aboard a SpaceX Falcon 9 from Cape
Canaveral on November 15, 2018. The satellite was boosted to a
geosynchronous orbit in the crowded slot located at 26.5° East
longitude, parking it directly above the Democratic Republic of Congo.
After tests were completed, a ceremony inaugurating the satellite as
“Qatar OSCAR-100”, or QO-100, was held on February 14, 2019, making it
the 100th OSCAR satellite launched by amateurs.
Sadly for hams in the Americas and most of eastern Asia, QO-100 is
out of range. But for hams anywhere from coastal Brazil to Thailand, the
satellite is visible 24 hours a day. The equipment to use it can be a
bit daunting, if the experience of this amateur radio club in Norway
is any indication. They used a 3-meter dish for the 2.4-GHz uplink,
along with a string of homebrew hardware and a lot of determination to
pull off their one contact so far, and this from a team used to bouncing
signals off the Moon.
Receiving signals from QO-100 is considerably easier. A dish in the
60-cm to 1-meter range will suffice, depending on location, with a
decent LNB downconverter. Pretty much any SDR will do for a receiver. An
alternative to assembling the hardware yourself — and the only way to
get in on the fun for the two-thirds of the planet not covered by the
satellite — would be to tune into one of the WebSDR ground stations that
have been set up. The British Amateur Television Club and AMSAT-UK,
located at the Goonhilly Earth Station, have set up an SDR for the narrowband transponder that you can control over the web. I used it to listen in on a number of contacts between hams the other night.
It’s hard to overstate the importance of QO-100. It’s the first ham
repeater in geosynchronous orbit, as well as the first DATV transponder
in space. It’s quite an achievement, and the skills it will allow hams
to develop as they work this bird will inform the design of the next
generation of ham satellites. Hats off to everyone who was involved in
getting QO-100 flying!