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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2answers
634 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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1answer
1k views

Command-line satellite tracking software

Is there any software similar to Gpredict but which can be used without a GUI and can control rotor Az/EL and radio doppler shift? I'm using Linux in particular, especially Ubuntu 14.04. Currently, I ...
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1answer
571 views

What determines the optimum frequency range for the transmission of signals?

What determines the optimum frequency range for the transmission of signals in a system that's transmitting electromagnetic signals between an antenna on the surface of the earth and an orbiting ...
3
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1answer
149 views

How much RF power should I expect to receive from a satellite?

I am trying to receive beacon from the analog satellites and observe its power on signal analyzer.I am using a 15dB gain and LNA with a 40dB gain. I am trying satellites like Ho-68(-81.64 dB at 56 deg ...
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1answer
246 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!
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438 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 ...
3
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4answers
281 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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0answers
109 views

Transmitting to and from low earth orbit? [duplicate]

I'm a hobbyist and I'm currently thinking about building a CubeSat. I'm currently designing PCBs, casing, etc. I was wondering what variables are involved with sending data to and from 250 km - 350 km ...
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2answers
176 views

Identifying signals in the satellite exclusive band

I have just started playing with SDR so I downloaded the relevant amateur band plan for my location, the UK. Tuning around I found things like POCSAG/FLEX pagers as expected and amateur radio (e.g. ...
6
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1answer
616 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 ...
3
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1answer
270 views

For Linear Transponder satellites, do I transmit on USB or LSB?

I'm in charge of our Field Day satellite communication, and I'm going to try and do this via SSB on one of the SSB satellites. I know they invert the signal, but is the convention to transmit on USB ...
3
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1answer
183 views

What is the largest amateur satellite in orbit through 2014?

What is the largest, and what were the dimensions of the largest amateur radio designated satellite in Earth orbit as of, or up until, 2014 other than the International space station.
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866 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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2answers
221 views

What will I need to receive the ICE/ISEE-3 transmitter?

The ICE/ISEE-3 spacecraft, launched in 1979, is due to pass by the earth in August, 2014. It was commanded to power down completely years ago, but it appears to have failed to do so, and while it ...
9
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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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1answer
92 views

Transmitting Offset for sats

I found some pages on info for satellites, and I got different results. Some said to shift the transmit frequency as well as the receive, some said to keep the transmit the same, but shift the receive ...
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3answers
10k 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
301 views

Where to find All Space Station Frequencies?

I am trying to make a list of all ISS downlink/uplink frequencies including ham bands and non-ham bands for a net I just started up, the Amateur Satellite net. Where can I find all of this? I can ...
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2answers
304 views

How far from earth do FCC regulations apply?

So, I know people in the space station need a HAM radio license for operation. How Far exactly from earth do you have to be to transmit any RF wave you want without a license?
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3answers
114 views

Why do satellite tracking programs have to be updated?

So I've heard every once and a while you have to update your satellite tracking software because of the fact that the satellites are falling towards Earth. Why can't the program automatically ...
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1answer
88 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? ...
3
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1answer
910 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, ...
5
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2answers
79 views

Website for Sat details

I used to use the Amsat website for finding out the status of Sats and other info, like operating frequency etc. It was proving useful, and I like the pass predictor also. Seems nowadays though there'...
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2answers
259 views

Why do satellites receive and transmit on different bands?

Most satellites I've found transmit on VHF and receive on UHF or vice versa. Why is this? I would think there's enough space on a single band.
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1answer
860 views

What is spin fading in satellite signals?

Why do signals from satellites experience "spin fading" as the satellite rotates? What are the effects that spin fading has on a radio signal? From test question: T8B09
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1answer
198 views

How to talk to the ISS

I have a UHF/VHF transceiver capable of transmitting on UHF and receiving on VHF or vice versa on channel mode. I finally got a directional Yagi antenna so reception/transmission shouldn't be a ...
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2answers
688 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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2answers
344 views

Have hams ever used (clusters of) geostationary satellites as passive microwave reflectors?

A number of geostationary satellites are quite large and/or appear in clusters. Moreover, many of them have large reflectors pointing to Earth (e.g. satellite TV sats). Finally, these satellites are ...
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3answers
674 views

What gain do I need to talk to SO-50 with my HT?

My HT has 5 W of power, a sensitivity of about 0.2 µV, and I would like to talk to the SO-50 with it. How much gain do I need in my antenna to make this work?