Similar to commit 33a8d1c for RTL-SDR, this uses two lookups in a
256-element LUT instead of one lookup in a 65536-element LUT, which
saves a bit of CPU cache. It also eliminates a dependency on the
host's byte ordering.
Signed-off-by: Eric Wild <ewild@sysmocom.de>
To allow switching between transmit and receive mode within a single
flow graph, I've followed the model used by the BladeRF: I factored
common code into hackrf_common.cc and hackrf_common.h, and created a
"_devs" map there to keep track of which devices have been previously
opened. Shared pointers are used to track how many source & sink blocks
are using a particular device.
Because some properties (center frequency, sample rate, bandwidth, RF
amplifier state, bias tee) are shared between receive and transmit, the
blocks defer setting these until receiving or transmitting is started.
That way a source and sink can safely use different values for these
properties, and the correct values are set during T/R switching.
Because the HackRF driver and/or hardware does not seem to fully
transmit all samples sent to it, the code adds some silence to the end
of transmissions to ensure all samples are transmitted.
I've also replaced boost with C++11 code where possible.
From: Clayton Smith <argilo@gmail.com>
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
This allows a block to enable an associated driver to begin
transfering data just before we start to execute the scheduler.
The end result is that this reduces latency in the pipeline
when dealing with audio devices, usrps, etc.
the following named gain stages are available:
RF: MGA-81563, switchable 0 or 14dB
IF: MAX2837 LNA, 0 to 40dB in 8dB steps
BB: MAX2837 VGA, 0 to 62dB in 2dB steps
features:
- gain control for LNA & VGA
- frequency error correction
- automatic baseband filter
- up to 20M sampling rate
limitations:
- no DC offset correction implemented (yet)
- no RX preamplifier control (disabled by default)
- high sampling rates may not work on slow machines
Clayton Smith
Wim Lewis
Dimitri Stolnikov