Hello Marcus, Many thanks for your reply. The ground station is intended to primarily support future educational CubeSat projects so it's difficult to say exactly what communications protocols will be used but you are right to assume common amsat modes. Currently we are developing a 1U cubesat that will use a 9.6 kbps GFSK/ASM+Golay/Reed Solomon configuration. However it might be of interest in the future to add support for reception of higher frequencies and data rates (say amateur S-band for example) which would mean adding another SDR to the same PC and there I'm worried about creating a bottleneck in terms of computing power. Thank you for the links I will have a look and investigate further.
Best regards, Martin On Fri, May 21, 2021 at 11:16 AM Marcus Müller <[email protected]> wrote: > Hi Martin, > > that's a bit of a wide field there :) In essence, there's not a single > answer to your > question: whether your hardware is sufficiently fast depends on what you > do with it! > > For example: 192 kb/s is really not much data to process, if there's a > simple (say, > Hamming(4,7) ) error-correcting code to be decoded on it. It's going to be > tough to > calculate if it's been through a large LDPC code and you want to do 50 > iterations of a > message passing decoder to really get even the last bit out of your > channel. > > But, you say "amateur satellite communications", which probably at a first > approximation > means you're using modes that are currently common in that community, or > such that are > currently constructed with complexity in mind. So, yeah. Most things > *should* work on the > four 1.5 GHz ARM Cortex-A72 cores of a raspberry pi 4 Model B. Note that > there's very > different Raspberry Pi models, so make sure you get the latest generation. > Also note that > your Raspberry Pi doesn't have to do *all* the work, if in doubt: for > example, the > relatively compute-intense steps could be, on demand, done on a laptop > with significantly > more computational power. > > So, it should work. However, that's a "should": I've got exactly zero > knowledge of people > who have done that, and a back-of-envelop calculation saying, hm, yeah, > that compute power > should suffice assuming the usage of sufficiently optimized software > doesn't say > sufficiently optimized software is available to you. But honestly, I think > there's really > a treasure trove of online information and working groups on that topic. > Maybe pay the GNU > Radio Amateur Radio Working Group a virtual visit [1]; I'm sure there's > much experience > with satellite comms in that channel. If text-chatting isn't very much > your thing, maybe > also try showing up to one of their monthly video calls[2], and hang > around before or > after the invited talk and chat a bit. > > Of course, as the largest community of citizen-operated satellite > groundstations, I bet > satnogs[3] has guidance on hardware. I do know they have raspberry Pi > images, but I > honestly don't know whether they're doing the digital communications part > on that, or > whether they are just recording the spectrum and maybe do some simple > demodulation (FM > demod?). Admittedly, and regrettably, not my prime area of expertise. > However, whenever I > meet satnogs people, they're a friendly bunch! They have a well-kept > online forum[4], > that's very active, and also a matrix presence[5]. > > Best regards, > > Marcus > > [1] via Matrix chat: #HamRadio:gnuradio.org; easily reachable via > https://chat.gnuradio.org/#/room/#HamRadio:gnuradio.org > [2] https://wiki.gnuradio.org/index.php/Talk:HamRadio > [3] https://wiki.satnogs.org/Main_Page > [4] https://community.libre.space/t/new-users-welcome/29 > [5] #satnogs:matrix.org (I think you really might want to have a Matrix > account on some > arbitrary homeserver ;) ) > > On 21.05.21 10:20, Martin Elfvelin via USRP-users wrote: > > Hello all, > > > > I'm building a ground station for amateur satellite communications on > the VHF and UHF > > bands using a B210. The SDR will be connected to a mini-pc and I'm > trying to figure out > > the system requirements. The PC will be controlling the SDR, running the > signal > > processing at low data rates (4k8 - 19k2 bps) as well as controlling > other hardware. > > Basically the PC is the brain of the ground station. I've seen people > making ground > > stations with Raspberry Pi but I'm wondering if 1.5 GHz quad core is > enough processing > > power in this case. Any help would be much appreciated. > > > > Best regards > > Martin Elfvelin > > > > _______________________________________________ > > USRP-users mailing list -- [email protected] > > To unsubscribe send an email to [email protected] >
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