diff options
| -rw-r--r-- | host/lib/usrp/dboard/db_tvrx.cpp | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/host/lib/usrp/dboard/db_tvrx.cpp b/host/lib/usrp/dboard/db_tvrx.cpp index 6b71a3c6e..1cb74c5ae 100644 --- a/host/lib/usrp/dboard/db_tvrx.cpp +++ b/host/lib/usrp/dboard/db_tvrx.cpp @@ -373,11 +373,29 @@ void tvrx::set_freq(double freq) { } /*********************************************************************** + * Get the alias frequency of frequency freq when sampled at fs. + * \param freq the frequency of interest + * \param fs the sample rate + * \return the alias frequency + **********************************************************************/ + +static double get_alias(double freq, double fs) { + double alias; + freq = fmod(freq, fs); + if(freq >= (fs/2)) { + alias = fs - freq; + } else { + alias = freq; + } + return alias; +} + +/*********************************************************************** * RX Get and Set **********************************************************************/ void tvrx::rx_get(const wax::obj &key_, wax::obj &val){ named_prop_t key = named_prop_t::extract(key_); - int codec_rate; + double codec_rate; //handle the get request conditioned on the key switch(key.as<subdev_prop_t>()){ @@ -410,9 +428,7 @@ void tvrx::rx_get(const wax::obj &key_, wax::obj &val){ * or if it will fall within Nyquist. */ codec_rate = this->get_iface()->get_codec_rate(dboard_iface::UNIT_RX); - if(codec_rate/2 > tvrx_if_freq) val = _lo_freq; - //ok take a deep breath i am positive there is an easier way to get this number - else val = _lo_freq - tvrx_if_freq - (tvrx_if_freq-codec_rate)*int(tvrx_if_freq / (codec_rate/2)); + val = (_lo_freq - tvrx_if_freq) + get_alias(tvrx_if_freq, codec_rate); return; case SUBDEV_PROP_FREQ_RANGE: |