From 3f9abbdf92701ca747f404082333673ed46b61f7 Mon Sep 17 00:00:00 2001 From: Vadim Yanitskiy Date: Fri, 10 Aug 2018 05:29:23 +0700 Subject: apps/grgsm_trx: add baseband frequency shift feature An ability to shift the baseband frequency would allow one to run both base stations and (OsmocomBB-based) mobile stations on any frequency (e.g. in 2.4 GHz WiFi band)! This is achieved by adding a given frequency offset to the result of "ARFCN -> RX/TX frequency" calculation. Usage example: grgsm_trx --freq-offset -500M Both RX (Downlink) and TX (Uplink) frequencies will be shifted by 500 MHz back, e.g. tuning request to ARFCN 105 would result in tuning the radio to 456.0 MHz (instead of 956.0 MHz). Related: OS#3520 (https://osmocom.org/versions/136) Change-Id: I42e397e47402a87f4141ef31b25eff4c8c1267e2 --- apps/grgsm_trx | 14 +++++++++++++- python/trx/radio_if.py | 14 +++++++++++++- 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/apps/grgsm_trx b/apps/grgsm_trx index 1c0581f..45312e6 100755 --- a/apps/grgsm_trx +++ b/apps/grgsm_trx @@ -25,6 +25,8 @@ import signal import getopt import sys +from gnuradio import eng_notation + from grgsm.trx import ctrl_if_bb from grgsm.trx import radio_if from grgsm.trx import fake_pm @@ -45,6 +47,7 @@ class Application: # PHY specific phy_sample_rate = 4 * 1625000 / 6 + phy_freq_offset_hz = None phy_tx_antenna = "TX/RX" phy_rx_antenna = "RX2" phy_rx_gain = 30 @@ -67,6 +70,10 @@ class Application: self.bind_addr, self.remote_addr, self.base_port) + # Optional frequency offset + if self.phy_freq_offset_hz is not None: + self.radio.freq_offset_hz = self.phy_freq_offset_hz + # Power measurement emulation # Noise: -120 .. -105 # BTS: -75 .. -50 @@ -110,6 +117,7 @@ class Application: " -G --tx-gain Set TX gain (default %d)\n" \ " --rx-antenna Set RX antenna (default %s)\n" \ " --tx-antenna Set TX antenna (default %s)\n" \ + " --freq-offset Shift baseband freq. (e.g. -500M)\n" \ " --ppm Set frequency correction (default %d)\n" print(s % ( @@ -128,7 +136,7 @@ class Application: "i:b:p:a:s:g:G:h", ["help", "remote-addr=", "bind-addr=", "base-port=", "device-args=", "sample-rate=", "rx-gain=", "tx-gain=", - "ppm=", "rx-antenna=", "tx-antenna="]) + "ppm=", "rx-antenna=", "tx-antenna=", "freq-offset="]) except getopt.GetoptError as err: # Print(help and exit) self.print_help() @@ -167,6 +175,10 @@ class Application: self.phy_tx_antenna = v elif o in ("--ppm"): self.phy_ppm = int(v) + elif o in ("--freq-offset"): + # Convert /\d+(\.\d+)?(M|k)?/ to Hz + offset_hz = eng_notation.str_to_num(v) + self.phy_freq_offset_hz = offset_hz def sig_handler(self, signum, frame): print("Signal %d received" % signum) diff --git a/python/trx/radio_if.py b/python/trx/radio_if.py index d2afcf6..407e724 100644 --- a/python/trx/radio_if.py +++ b/python/trx/radio_if.py @@ -4,7 +4,7 @@ # GR-GSM based transceiver # Follow graph implementation # -# (C) 2016-2017 by Vadim Yanitskiy +# (C) 2016-2018 by Vadim Yanitskiy # (C) 2017 by Piotr Krysik # # All Rights Reserved @@ -29,6 +29,7 @@ import grgsm from math import pi +from gnuradio import eng_notation from gnuradio import digital from gnuradio import blocks from gnuradio import uhd @@ -59,6 +60,7 @@ class dict_toggle_sign(gr.basic_block): class radio_if(gr.top_block): # PHY specific variables + freq_offset_hz = None rx_freq = 935e6 tx_freq = 890e6 osr = 4 @@ -274,11 +276,21 @@ class radio_if(gr.top_block): return self.ppm / 1.0e6 * 2 * pi * fc / self.sample_rate def set_rx_freq(self, fc): + if self.freq_offset_hz is not None: + fc += self.freq_offset_hz + print("[#] Shifting RX freq. to %s (offset is %s)" + % (eng_notation.num_to_str(fc), + eng_notation.num_to_str(self.freq_offset_hz))) self.phy_src.set_center_freq(fc, 0) self.rotator_src.set_phase_inc(self.calc_phase_inc(fc)) self.rx_freq = fc def set_tx_freq(self, fc): + if self.freq_offset_hz is not None: + fc += self.freq_offset_hz + print("[#] Shifting TX freq. to %s (offset is %s)" + % (eng_notation.num_to_str(fc), + eng_notation.num_to_str(self.freq_offset_hz))) self.phy_sink.set_center_freq(fc, 0) self.rotator_sink.set_phase_inc(-self.calc_phase_inc(fc)) self.tx_freq = fc -- cgit v1.2.3