7 Dec
2020
7 Dec
'20
10:48 p.m.
Hello list!
I've been digging a bit into the osmo-bts project to explore the GSM
stack, and only ever see config information assuming you have a
full-duplex TRX radio. I have a HackRF One I'd like to use for TX and
an RTL-SDR I'd like to use for RX (both operating on the 900MHz GSM
band), but cannot seem to find any configuration information for setting
this up - even though I've seen some mentions in passing to osmo-bts-trx
supporing RTL-SDR devices. I really don't have the budget to drop a few
hundred more on a USRP device just to tinker with GSM and was hoping I
could get away with two dedicated radios.
Can anyone tell me 1. if this kind of setup is even supported and 2. if
so, point me to reference material that might help me make the connection?
Thanks in advance!
-Rob
--
==========
Robert Bates
Octobang
rob(a)octobang.com
https://keybase.io/arpieb
11:31 a.m.
1. if this kind of setup is even supported
It's not.
Hi Sylvain,
This answer made me curious. Is it because it is not implemented yet or
because you need an exact (same) clock for the Rx and Tx part. Or is it
because of something else.
Thanks in advance for the answer.
Kind regards
Philipp
11:58 a.m.
Hi,
This answer made me curious. Is it because it is not
implemented yet or
because you need an exact (same) clock for the Rx and Tx part. Or is it
because of something else.
You need the exact same clock (or at the very least phase locked ones,
you could have different sample rates if they are locked you can
always resample in software).
Then you also need to know absolute time sync (i.e. which sample of TX
matches exactly which sample on the RX side).
Theses requirements, while not impossible to achieve would impose some
hardware modifications to whatever cheap SDR you try to use (like
hackrf for TX and RTL-SDR for RX), making it hard to reproduce.
It would also required _a_lot_ of work on the software side to deal
with all the peculiarities of such a system.
And finally there are cheap-ish full duplex SDR.
So simply put, there is too high a cost and too low a reward to bother.
I mean, if someone has a spare 100kEUR in their couch cushion to
finance the dev, I'm sure I can get that implemented.
Cheers,
Sylvain
3:17 p.m.
Thanks for the quick reply. If you don't mind me asking, what would you
recommend as the least expensive option that you know is fully supported
by the Osmocomm stack?
-Rob
On 12/7/2020 6:13 PM, Sylvain Munaut wrote:
--
==========
Robert Bates
Octobang
rob(a)octobang.com
https://keybase.io/arpieb
1. if this
kind of setup is even supported
It's not.
Cheers,
Sylvain
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days inactive
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4 comments
3 participants
participants (3)
-
Philipp Psurek -
Robert Bates (Octobang) -
Sylvain Munaut