I'm working on a cubesat, and I want to communicate in the S-Band, arround 2.4GHz. And I'm searching for schematics of a transceiver example with arround 35 dBm of output power. If any have a .pdf, .sch or an image of schematics I appreciate it.


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    $\begingroup$ You want a schematic for an entire transceiver? You'll have to specify all kinds of things; modulation type, data rate, IF bandwidth, hand shaking, etc. Can you just look up a software defined radio schematic for that range or a WiFi or other data radio to start with? en.wikipedia.org/wiki/List_of_WLAN_channels $\endgroup$ – uhoh Oct 28 '20 at 8:40
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    $\begingroup$ I want the schematics of the transceiver, not the MCU that controle that, just the RxTx and the LNA. I can work with 10kbps and modulation ASK or OOK. Anyway i can adapt. Is for a cubesat that go to be in Moon orbit. Im checking the CC2500 from TI $\endgroup$ – Valentino Zaffrani Oct 28 '20 at 9:09
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    $\begingroup$ What's "just the RxTx"? You're still vastly underdefining the things you need. Please edit your question to very clearly write requirements for what you need and what you don't need. Also, honestly, what does asking for a transceiver schematic have to do with space exploration? The only option this would be on-topic according to this site's help pages would be if this was "Systems with potential use in space", and sorry, asking for a random S-Band transceiver schematichas nothing to do with how you'd design a space-hard transceiver, let alone one that works over space-typical distances. $\endgroup$ – user17550 Oct 28 '20 at 10:36
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    $\begingroup$ @MarcusMüller no love for this question, but it does clearly state it's for a cubesat. I think we can agree that is in the 'potential uses in space' bucket. $\endgroup$ – Organic Marble Oct 28 '20 at 11:54
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    $\begingroup$ @OrganicMarble Ufff ... if you're spending multiple 10k€ on putting a satellite into space, is "could someone send me a schematic, I have no experience desiging circuits" implying "no idea on layout", "little experience designing communication systems" a realistic question about a system with a space use? I mean, this is going to be one of the very important parts of your payload (satellites that can't communicate are completely useless). Asking about cheese recipes, because one wants to put dairy into space makes about as much sense, to me, as communications engineer. $\endgroup$ – user17550 Oct 28 '20 at 12:18

What you're asking:

Can I get a schematic of a transceiver that I can just drop into my satellite and it'll work?

What you should be asking is:

How can I define the requirements for a transceiver, so that someone designing transceiver systems can design one, and then someone designing transceiver hardware can draw a schematic fit for my application?

In the context of commmunications, requirements engineering start with a link budget. That's basically.

  1. How much data do I need to exchange, at which rate, with which probability of it failing?
  2. What are the regulatory constraints (power, frequency, ...) I'm subject to?
  3. What are the physical and cost constraints I'm under (size of antenna, power usage, latency, weight, vibration safety, space radiation hardness...)

Based on 1-3 you then either

  • Find an off-the-shelf system that fulfills these requirements (and if this is a control modem: DO THAT. You don't want to not have control of your satellite simply because someone inexperienced designed the modem.)
  • Design something based on these requirements.

This will include, among a lot of other things:

  • Required output power
  • Bandwidth
  • Oscillator frequency accuracy and stability
  • Linear/acceptable dynamic range for transmitter
  • Required sensitivity of the satellite-side receiver
    • from that, a maximum noise figure
  • Correction for Doppler (you're building a LEO... you do realize you have Doppler?) and symbol clock offset in general
  • ...

From these you can then define requirements on:

  • filters,
  • duplexers,
  • antennas,
  • amplifiers
  • mixers,
  • synthesizers

and the transmission scheme you want to use.

You write:

I can work with 10kbps and modulation ASK or OOK.

... red flag, neither are usually used in space comms, for good reason. (OOK also is never as spectral efficient as BPSK, and ASK is usually less spectrally efficient but in a few very specific corner cases, but requires a much higher power / lower noise for the same performance).

Really, wrong proposition.

You're putting something into space that isn't exactly cheap, and that you can't fix tomorrow morning if your transceiver doesn't work. You haven't even been able to write down requirements for a transceiver.

There's more than [one smallsat] and certainly a couple N·$10⁸-satellites that failed because there was a mistake in their communications design. You're very much setting yourself up for one. (Example - KRAKsat, though that failed on multiple fronts. Seriously, I don't want to hurt anyone's feelings, but reading that report just screams "maybe getting someone with experience wouldn't have been a bad idea and saved a lot of money" at every other sentence. But, you really want to read section 1.8. Inaccurate analysis of the missions requirements.).

  • $\begingroup$ This is true, but im just searching for a point to start, not a full design, just i want a schematic for reference $\endgroup$ – Valentino Zaffrani Oct 28 '20 at 13:56
  • $\begingroup$ then take a transistor and attach it to a GPIO and an antenna. It also emits electromagnetic waves. And it's about as useful as any other reference schematic that we can give you, lacking specifications. $\endgroup$ – user17550 Oct 28 '20 at 13:57
  • $\begingroup$ I go to start with the CC2500 + LNA + PA, but maybe my post lack of specifications but at the point of a transistor? $\endgroup$ – Valentino Zaffrani Oct 28 '20 at 14:00
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    $\begingroup$ Why do you even think a CC2500 is the right tool? I'll stop responding now, because I repeat my point constantly: What you need is specifications first, decisions on what hardware to use later. It doesn't work the other way around. $\endgroup$ – user17550 Oct 28 '20 at 14:01

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