Questions tagged [satellites]

Amateur radio satellites refer to any artificial object in Earth orbit that are useful for amateur radio purposes.

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1answer
763 views

Why does Free space have the highest loss compared to other losses like atmospheric loss, feeder loss etc?

In a communication Satellite system, there are losses that occur when the signal is received at the antenna and then passed through a communication link to the output stage which could be the receiver....
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3answers
757 views

Website for satellite down/uplink frequencies and live footprint?

I am looking for a website that has the satellite footprint as well as the downlink freq. I just got a 2m/70cm handheld and want to see what I can pick up.
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Could not observe the Meteor M2 even though I scanned the sky at the time it passes with a high elevation degree (77). What might have happened?

I am currently trying to observe and obtain data from the meteorological satellites. I have constructed a V-dipole specifically for the 137 MHz and was able to observe the NOAA 15, NOAA 18, and NOAA ...
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1answer
37 views

How does one log a QSO via a cross-band repeater?

When working through a cross band repeater, either the two sides are using different bands or both sides are using two bands at once. At the same time, most if not all logging software (as well as ...
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1answer
108 views

Double Cross Dipole antenna for 437 MHz don't tune

I'm building a Double Cross Dipole antenna for 437 MHz to be used with a SDR receiver for CW cubesat. The idea is to follow this "classic" paper from Gerald Martes, KD6JDJ. I tuned every single dipole ...
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165 views

Ham Radio and Space Communications

I hear a lot of people talking about getting in contact with space with their ham radio. What do you hear? Do you talk to astronauts? Or: Is it just an expression?
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188 views

Using Satnogs' *.ogg files in GnuRadio flowgraphs

I want to use the *.ogg files available in Satnogs' database to test demodulation software for several satellites (using gnuradio). Can i use the ogg file source (available in gr-satnogs module) and ...
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0answers
60 views

Circular polarized antenna feed changes as I rotate it?

I had a 100cm prime focus dish laying around and I thought of making a circularly polarized feed for it, since it seemed pretty straightforward from what I've been reading. Helical feeds are supposed ...
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3answers
120 views

APT/LRPT images geotagging

I want to extend functionality of some open-source programs which decode APT and LRPT images (wxapt and glrpt). More specifically I want to add possibility to overlay geographical data such as land ...
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1answer
54 views

2 meter and 70cm OSCAR expected signal attenuation by topocentric elevation angle, chart?

On average, is there a chart, or formula, which shows an expected signal attenuation due to the elevation angle to the satellite's position? I understand that range (distance) is also going to affect ...
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2answers
133 views

Working satellite on 2 meters, at what arc distance to sun (center) will noise floor be problematic to a disruption of a communication path?

Is there some simple utility, or published set of charts, or suite of formulae, where one can approach the situation by inputting a space weather summary, (sunspots, various indexes, etc), the receive ...
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1answer
89 views

Kenwood TH-D72A and AO-91/92

I got a Kenwood HT and using it with the Elk Antenna On the radio, there is Tone and I set it to 67 Hz. I wasn’t able to break thru to the satellite and had it in Full Duplex mode. I can hear ...
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1answer
89 views

Where to find FM satellite information

I'm new to satellites and I am trying to find all the information for everything. Where can I find a list of all the operational FM amateur satellites with the down-link and up-link frequencies? ...
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1answer
1k views

Max El vs Max El Azimuth

I don't have much experience with amateur satellites and I went to the AMSAT website to track a few passes. Two of the terms are "Maximum Elevation" and "Max El Azimuth" I go to look up the terms, ...
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1answer
87 views

Gain of Yagi turnstile?

I am currently working on a system to communicate with amateur CubeSats. I have decided to use the turnstile crossed-dipole style yagi because it is relatively easy to construct and uses circular ...
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1answer
98 views

Is it possible to receive weather satellites with a ham radio rig? (Icom 910)

I would be interested in receiving weather satellites (NOAA and Meteor) with my Icom 910. It has very good filters and could be a better solution than a simple SDR. However, its manual specifies that ...
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1answer
72 views

Are there any satellite email reflectors?

I'm just getting started using amateur satellites and would like to subscribe to an email reflector, but I can't find one. Is there anything out there?
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48 views

What value goes in the AX.25 PID field if the Layer 3 protocol is not defined in the standard?

I am working on space-ground networking for a Cube Satellite, and one of our candidate Layer 2 protocols is AX.25. We haven't settled on a physical layer, but it's likely to be some form of quadrature-...
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1answer
227 views

How do amateur satellites stay consistently in the amateur-sat bands acoss the globe?

I understand that my local laws may differ but amateur radio satellites, by their very nature, orbit the earth going over several legal jurisdictions. Are satellite bands the same internationally? If ...
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2answers
404 views

BPSK raw data aquisition with HDSDR and FLDIGI

I was playing with HDSDR+ExtIO and Ettus USRP1 to track a BPSK signal. In the end I successfully heard the signal. But I would like to see the data, I mean the raw data (HEX values). For that I tried ...
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2answers
396 views

How do I listen to the amateur radio satellites?

I'm new to amateur radio, and I would like to listen to those satellites in the orbit. Where do I start? What types of amateur radio satellites exist?
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3k views

Can I build a radio telescope out of a parabolic TV satellite dish?

I have the possibility to buy a very inexpensive 2.4m parabolic satellite dish and I would like to build a radio telescope from it. Originally this dish was designed to be a satellite TV antenna. ...
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37 views

Noise Floor when receiving Es'hail 2

I'm currently trying to receive the Es'hail 2 satellite using a standard TV LNB, 60cm dish and RTL-SDR. My dish is slightly offset by 2 degrees, and my SNR is only about 15dB unfortunately. My main ...
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11k views

Calculating Doppler Shift for satellites

If I know how fast a satellite is moving through space, how can I calculate the doppler shift for the pass?
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1answer
105 views

How can I improve my Es'Hail 2 reception?

I'm using an RTL-SDR to receive Es'Hail 2. My chain is as follows in order: 60 cm TV Satellite dish pointing 2 degrees off Es'Hail 2 Universal LNB (from TV company, not really a stable frequency). ...
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1answer
2k views

Why would you need a signal generator to receive early satellite transmissions?

I recently watched, on You Tube, a NOVA program about the British school masters and students who were the first to publish the news that the Soviets had started launching satellites from a new launch ...
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528 views

Who funds amateur radio satellites?

I am currently studying for my Technician Exam and I am amazed at the sheer number of amateur radio satellites in orbit. Knowing how expensive it is to launch something into space, and assuming there ...
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Any reception reports from ExseedSAT1 yet?

My answer to the question Where can I find the TLE of ExseedSat 1, India's first ever private LEO satellite? is currently that while 60+ objects are being tracked from this mutli-payload launch, ...
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2answers
2k views

Antenna polarization when dealing with satellite communications

It's easy to understand, conceptually anyway, the difference between a horizontally polarized antenna and a vertically polarized one, when referenced to ground. However, when they are pointed nearly ...
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1answer
115 views

Help understanding this tweet about receiving images from satellite behind the Moon

This GBTimes article A tiny Chinese satellite is orbiting the Moon and allowing radio amateurs to download images links to this tweet which shows a high gain UHF? antenna pointed at the Moon, and that'...
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224 views

Warbler vs SoundModem

I'm trying to decode a BPSK 1200 (with no success). In this endeavor I tried both SoundModem and Warbler. The scenario here is the following: Ettus receiver + HDSDR with speaker plugged into mic via ...
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2k views

APRS digi path for ISS digipeater?

So when I try to work the ISS digipeater, what should I set the digi path to be? My setup is a 5 W HT with a 2 m yagi connected to my phone with APRSDroid. I've tried the past few nights with ...
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256 views

Doppler shift compensation without using predictive modelling

Doppler shift mitigation has been studied extensively in the literature. In my implementations of satellite receivers (using GNU Radio), I use predicted Doppler shift from a software (GPredict) to ...
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141 views

What wireless communication technologies can travel long distances with a high bandwidth?

I couldn’t find a better place to ask this question, so I have asked it here. I am looking to transmit and receive internet connectivity wirelessly over a distance of 6 miles (9.7 km) with a minimum ...
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2answers
2k views

Are satellites Left or Right hand circularly polarized?

I'm thinking of building some helical antennas for satellite work. I want to know which way to wind them. If satellites are spinning randomly, how can we know if they are left hand or right hand ...
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2answers
907 views

What is Circular Polarization?

So I just learned that a satellite does not send out a circularly polarized signal, it just switches orientation slowly when it topples through space. I thought that because they were spinning, the ...
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1answer
603 views

What is the turn spacing on a Helix Antenna?

I want to do some satellite communication so I thought why not build my own helix antenna. I found this page: Helix antenna design and construction details The most things are clear except for the ...
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2answers
177 views

I would like to listen to a red roadster in space

I have been listening for signals (any) of the Space-X Falcon Heavy. Just out of curiosity. And I am wondering if anyone has received any. According to the Falcon-9 User Guide table 4.6 looks like ...
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474 views

Are there any satellites with 435 MHz uplink?

I have a transceiver working in the 435 MHz ham band. I want to test my uplink capability by communicating with satellites operating in this band. Are there any digital satellites which I can use for ...
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4answers
227 views

Who regulates ham radio satellites?

I have doubts regarding the control authority of the amateur radio satellites, because recently we have drastic changes to Internet control by FCC as the next major decentralized communication system ...
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692 views

Can there be (long range) propagation of HF from satellites?

HF transmissions from the ground can be reflected by the ionosphere leading to very long distance propagation. Satellites in low Earth orbit (160 km to 2,000 km) fly within the ionosphere (60 km to ...
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3answers
312 views

Would the antenna described work?

For reception of amateur radio satellites, turnstile antennas (consisting of two crossed dipoles fed out-of-phase) are often used. I've recently had an idea - what if two half-wavelength dipoles are ...
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1answer
210 views

What happened to AMSAT-Phase 3E?

The web pages related to the unlaunched satellite were last updated in 2007, so I wonder - where is it now? Is it going to be launched someday?
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1k views

How to transmit images and video through a hurricane?

Background You're in the path of a hurricane, and the eye just passed over your head. There is no electricity (apart from your own generator or battery), there is no mobile network and there is ...
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285 views

Can sub GHZ frequency can be used in space communciation?

Is it possible for a sub GHZ frequency (Say 300 Mhz) can be used for space communication for small satellites such as a cubesat? What are the advantages and disadvantages for this.
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1answer
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Could UHF Earth-Satellite-Earth bouncing of signals off of this large metallized foil satellite be feasible?

The July 14, 2017 NASA Spaceflight article Soyuz 2-1A launches with Kanopus-V-IK and over 70 satellites says: Mayak is a three-unit CubeSat which was built by Tvoii Sektor Kosmosa – or “Your Sector ...
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2k views

doppler LEO satellite

I am trying to model Doppler shift of LEO satellite, From my research so far I have come across the following formula: \begin{equation} \frac{f_r}{f_s}=\frac{1-\frac{u}{c}cos\theta}{\sqrt{1-\frac{u^2}...
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773 views

Store-and-forward capable satellites in operation?

The amateur satellite community used to have a small fleet of pacsat satellites (AO-16 and friends), which were capable of store-and-forward message passing: you could upload messages to the LEO ...
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1answer
646 views

Doppler Shift Compensation in Inter Satellite Communication

I am currently doing a project in the area of optical inter-satellite communication (GEO-LEO). I am using a optical carrier of 281 THz, and the Doppler shift corresponding to it is ±7 GHz. I ...
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1answer
275 views

Are there any satellites in UHF that do not use AX.25? Which of them are in working state? Is the communication to them open?

I have a custom digital transceiver and will like to communicate with digital satellites in the UHF band. It might be fun to try different protocols other than commonly used (like AX.25) as well!