Vadim Yanitskiy has uploaded this change for review. ( https://gerrit.osmocom.org/10770
Change subject: apps/grgsm_trx: add baseband frequency shift feature ...................................................................... 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 --- M apps/grgsm_trx M python/trx/radio_if.py 2 files changed, 23 insertions(+), 2 deletions(-) git pull ssh://gerrit.osmocom.org:29418/gr-gsm refs/changes/70/10770/1 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 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 @@ # 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 @@ 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 @@ " -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 @@ "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 @@ 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..71d771b 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 <[email protected]> +# (C) 2016-2018 by Vadim Yanitskiy <[email protected]> # (C) 2017 by Piotr Krysik <[email protected]> # # All Rights Reserved @@ -59,6 +59,7 @@ class radio_if(gr.top_block): # PHY specific variables + freq_offset_hz = None rx_freq = 935e6 tx_freq = 890e6 osr = 4 @@ -274,11 +275,19 @@ 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 %d MHz (offset is %d Hz)" + % (fc / 1e6, 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 %d MHz (offset is %d Hz)" + % (fc / 1e6, 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 -- To view, visit https://gerrit.osmocom.org/10770 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: gr-gsm Gerrit-Branch: master Gerrit-MessageType: newchange Gerrit-Change-Id: I42e397e47402a87f4141ef31b25eff4c8c1267e2 Gerrit-Change-Number: 10770 Gerrit-PatchSet: 1 Gerrit-Owner: Vadim Yanitskiy <[email protected]>
