Skip to main content

Questions tagged [satellites]

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

Filter by
Sorted by
Tagged with
2 votes
0 answers
71 views

how to avoid overflow using a python block in GNUradio

I am implementing this code in an embedded python block in GNU Radio to received a stream of bits and extract a part of that stream, but I get "OsOOsOOsOOsOO" in the console and the CPU ...
ANDRES FELIPE RODRIGUEZ RENDON's user avatar
3 votes
0 answers
119 views

Tuning an L-band dish for receiving GOES signals

I've encountered some challenges with my ground station intended for receiving images from GOES satellites, and I'm seeking your expertise to troubleshoot the issue. Here are the system specifications:...
Moses Browne Mwakyanjala's user avatar
6 votes
1 answer
1k views

Why not access the AO-91 satellite at night during eclipse?

According to amsat-uk.org, the AO 91 satellite should not be accessed during eclipse because it is near EOL. AO-91 (RadFxSat / Fox-1B) Near end of life. If you find it on, do not attempt to access in ...
KJ7LNW's user avatar
  • 723
4 votes
0 answers
60 views

Optimizing Half-Duplex Sequencing: Consolidating RF and Power Connections with Bias-T and VOX

I've successfully implemented a half-duplex sequencing mechanism, which I've illustrated below. The outdoor components are represented in green. In my current setup, I utilize a PLC to control both an ...
Moses Browne Mwakyanjala's user avatar
5 votes
1 answer
834 views

What's the protocol when making a call on the ISS repeater?

I have mostly only used non-crowded 2 meter repeaters, but recently I tuned my radio to the downlink frequency: 437.8 mhz while the ISS was passing overhead - just to listen. What I heard was people ...
scm's user avatar
  • 193
0 votes
1 answer
227 views

TV Coax cable for QFH antenna

I'm new to this hobby and I'm trying to make me a QFH antenna for NOAA satelites myself. I would like to know if I can use AC15-380WH 4/8K TV coax cable with double ...
Marcel Kopera's user avatar
2 votes
1 answer
52 views

Half-duplexing with mechanical SPDT switches

I was able to implement a half-duplex system using an SPDT switch and a relay board and tested it in a lab environment. I'm about to test it against orbiting CubeSats. I understand that the return ...
Moses Browne Mwakyanjala's user avatar
3 votes
1 answer
95 views

Why some QO-100 setups use GNSS

I'm looking into building a QO-100 setup, but am struggling to find good/easy to understand resources for beginners which would outline the most common approaches and their pros/cons. From what I ...
Tadej Gašparovič's user avatar
-2 votes
1 answer
101 views

How do the governments trace the frequencies such as satellites?

During Woman, Life, Liberty protests Elon Musk activated Starlink in Iran and yesterday reported that 100 devices are active right now. Since it is illegal to have the device in Iran, how do the ...
ElectronSurf's user avatar
11 votes
4 answers
6k views

How do GPS receivers communicate with satellites?

I have a Technical Amateur Radio license so I know the basics of wavelengths. What I'm researching is how GPS works. From what I've read, there are frequencies such as L1, L2, and L5 uses in GPS ...
john_ham_radio's user avatar
3 votes
1 answer
94 views

Is there a list of public datacasts?

I know several datacasts which are free to almost free to receive. Like there is the outer(other-)net, which can be received using a lora module - it contains a subset of APRS messages and weather ...
NajiqAlef's user avatar
2 votes
1 answer
230 views

Link budget validation for a UHF satellite ground station

I built a UHF satellite ground station. It has a yagi with G=16.1dBi and an LNA with G=20.1dB. It’s a 430 - 450 LNA with NF=0.68. The RF cable, rg174/u has I think close to a 1dB/m, which would mean ...
Moses Browne Mwakyanjala's user avatar
0 votes
1 answer
189 views

YouLoop antenna for amateur satellite reception

I recently learned about the commercial YouLoop antenna and it seems to be quite simple to set up. They said it was possible to receive satellite signals on amateur VHF (e.g. NOAA and other CubeSats ...
Moses Browne Mwakyanjala's user avatar
3 votes
0 answers
58 views

What could cause an IQ diagram to shapeshift randomly?

I'm trying to interface a DVB-S2 transmitter to a DVB-S2 demodulator - for now with a direct cable+attenuator link. Both are set up exactly with the same parameters (same carrier frequency [2150MHz], ...
Mister Mystère's user avatar
1 vote
1 answer
500 views

AX.25 protocol packet size

I am new to the world of amateur radio and I am carrying out a university project concerning the communication between satellites and ground stations. My question is: What is the packet size of the AX....
BRU's user avatar
  • 11
0 votes
1 answer
534 views

How would I calculate the diameter of an dish from antenna gain, or effective aperture?

So far I've calculated the effective aperture using an equation. However I was wondering how to calculate dish diameter using the gain calculated earlier and if there's an equation for this?
ijq12's user avatar
  • 1
2 votes
1 answer
610 views

How do phased array antennas work when they produce spot beams?

Background In a lot of literature regarding satellite communications with phased arrays, you'd see this kind of image: Conceptually, I get the basic concept of how this works - a bunch of small ...
0xbad1d3a5's user avatar
2 votes
1 answer
235 views

The Terrestar Genus was able to talk to a GEO satellite in a smartphone-sized package, where's the antenna on this thing?

Background I'm doing some research on a company called ASTS who claims to be able to connect to regular smartphones from a satellite. Initially I wrote off their claims, but after looking into it a ...
0xbad1d3a5's user avatar
2 votes
4 answers
711 views

UHF/VHF Satellite ground station with a discone antenna

I'm in the process of building an SDR-based satellite ground station using a discone. The discone is chosen due to its wider frequency range. Additionally, a dual-band LNA with around 20 dBi in both ...
Moses Browne Mwakyanjala's user avatar
3 votes
0 answers
318 views

Turnstile antennas with a "single-point feed": what's the antenna theory behind this, and how do I build/model it?

The conventional turnstile antenna uses a 1/4wl phasing line between the crossed elements, to get the required phase shift. 4nec2 includes an example file, though, of a circularly-polarized Yagi using ...
1200bps's user avatar
  • 31
7 votes
1 answer
134 views

Are there any active ham satellites orbiting that use the 5cm band?

I see that 5cm is available for satcom in amateur radio. Are there any active satellites for that? If so, what satellites and are their TLE's available?
KJ7NLL's user avatar
  • 73
1 vote
2 answers
196 views

TCP/IP-based antenna controller for a UHF/VHF satellite ground station

I am looking for an antenna rotor controller with a TCP/IP interface. Most rotor controllers (like the ones for YAESU series) are either serial or USB-based. I was wondering if there are alternatives ...
Moses Browne Mwakyanjala's user avatar
2 votes
2 answers
704 views

How much dB gain do you need from an LNA in front of an antenna for great low-signal reception from satellites in the 2m and 70cm bands?

We are building a multi-stage LNA for a TR module we are building in the 144MHz and 440MHz range. This LNA we are considering (Qorvo QPL9547) provides about 22dB gain in the 2m and about 27dB in the ...
KJ7LNW's user avatar
  • 723
6 votes
1 answer
217 views

Has an amateur radio communication ever taken a path outside the Earth-Moon system?

As a bit of curiosity, I was wondering what the longest path ever used by amateur radio operators has been. Of course the opposite side of the Earth is no problem with a good HF station. And you can ...
Phil Frost - W8II's user avatar
3 votes
0 answers
98 views

Any tool for finding satellite passes that overlap *two* given locations?

gpredict is nice. Well, it's OK, to find the next passes for a set of satellites with sufficient elevation for one location. What I want is something where I can put in two coordinates, and get out ...
Thomas's user avatar
  • 744
2 votes
3 answers
114 views

what is the baseband for CATV?

I was reading on wikipedia this: the subscriber's television or a set-top box provided by the cable company translates the desired channel back to its original frequency (baseband) But when I ...
sumer fattoum's user avatar
2 votes
2 answers
2k views

How much of the 136 - 174 mhz spectrum is actually in use?

I know that 144-148 and 156-157 mhz ranges are in use, and various fire/ems/police, but outside of that, I see a lot of earth-to-space, weather stuff and space research allotments (talking about ...
Peggy Schafer's user avatar
5 votes
2 answers
2k views

Receiving the ISS SSTV: dipole antenna configuration and orientation

In short I am trying to receive SSTV Images from the ISS (145.8Mhz) and I all have is a simple "bunny ears" dipole antenna. In what configuration (straight, vee shaped, upside down vee, ...) ...
Steven's user avatar
  • 205
5 votes
2 answers
314 views

Calculating satellite passes without an internet tracker?

Situation: You want to know when a satellite will pass in order to receive an image transmission or to work an amateur satellite. However, you cannot access internet for whatever reason, and ...
Galaxy's user avatar
  • 199
0 votes
0 answers
48 views

How to decide between Dipole and Monopole antenna for Cubesat Uplink (433 MHz)? [duplicate]

We are currently deciding between a dipole and a monopole for uplink (435MHz) , while the monopole is easier to feed, we are unsure of how effectively we'll be able to implement the ground plane, ...
Rishabh Hulsurkar's user avatar
4 votes
1 answer
798 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....
Signal's user avatar
  • 43
2 votes
1 answer
118 views

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 ...
TEQATAR's user avatar
  • 43
1 vote
1 answer
275 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 ...
Ivan R2AZR's user avatar
1 vote
1 answer
402 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 ...
Carlo IU2KQB's user avatar
3 votes
3 answers
289 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?
hopefulhacker-Reinstate Monica's user avatar
3 votes
0 answers
226 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 ...
hjf's user avatar
  • 1,199
6 votes
3 answers
265 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 ...
Drobot Viktor's user avatar
3 votes
1 answer
72 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 ...
always_learning's user avatar
4 votes
2 answers
198 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 ...
always_learning's user avatar
2 votes
1 answer
211 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 ...
Engineer2021's user avatar
2 votes
1 answer
230 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 ...
Caphlp22's user avatar
3 votes
1 answer
133 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 ...
user3141592's user avatar
1 vote
1 answer
96 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?
Rick WR0H's user avatar
4 votes
1 answer
177 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-...
VE9PEG's user avatar
  • 41
3 votes
1 answer
247 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 ...
Amin Shah Gilani's user avatar
4 votes
2 answers
2k 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?
Sumithran's user avatar
  • 573
2 votes
2 answers
803 views

Using Satnogs' *.ogg files in GNU Radio 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 ...
Hayfa's user avatar
  • 23
2 votes
0 answers
44 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 ...
user14615's user avatar
  • 157
1 vote
1 answer
178 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). ...
jt.retro's user avatar
11 votes
1 answer
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 ...
John Warren's user avatar