*** UPDATE: use github n1gp/librtlsdr instead as it supports both	***
*** Linux and Windows builds and will be used for future updates	***

rtl_hpsdr is an RTL to HPSDR software translation server.

It currently builds and runs on Linux. It identifies and uses up to
seven (theoretically eight) USB RTL2832U-based DVB-T dongles. The
dongles can be set up with an up converter or use RTL direct-mode
for HF receive. Or direct input to provide it's native > HF receive
range.

The program can be passed in a variety of command line options.
One of which is a frequency offset not only for up converter use
but also to allow a full range of frequency options to HPSDR programs
that are coded to only allow the real HPSDR radio's (i.e. Hermes)
frequency range which is from 10KHz to 55MHz.

The main purpose of this program is to provide a mechanism that
allows RTL Dongle owners the ability to use them on HPSDR specific
software programs.

One such program, cuSDR64 has the ability to control and display
up to 7 rcvr slices simultaneously. With rtl_hpsdr, if your host
has the horsepower, you can run 7 RTL Dongles to emulate the HPSDR
rcvr. cuSDR64 also can be built and run on Linux.

Since the real HPSDR (i.e. Hermes) rcvr can do up to eight rcvr
slices, there is a concept of 'COPY' rcvrs in this server. This
would allow one to use HPSDR programs that expected more rcvrs
than were attached. Currently if a program request more rcvrs
than are actually attached the rtl_hpsdr server will make copies
of the last 'real' rcvr. This alows one to only have one RTL dongle
attached and run PowerSDR mRX which may expect up to four rcvr
slices.

Refer to: http://openhpsdr.org/softwareinfo.php  for a list of
HPSDR supported applications.

I have tested this only on cuSDR64, cuSDR32, and PowerSDR mRX.

I was successful running 7 RTL dongles simultaneously on a
Quad core ARM Cortex A9 based mini-pc, model EKB311
running a version of Picuntu, http://ubuntu.g8.net/

Useful documentation:
http://openhpsdr.org/support/Ozy/USB_protocol_V1.48.pdf
http://svn.tapr.org/repos_sdr_hpsdr/trunk/Metis/Documentation/Metis-%20How%20it%20works_V1.30.pdf

Feel free to fix / add / modify this program.
I'd appreciate keeping me updated, n1gp@hotmail.com


1. Dependencies

- At least one (and up to seven) RTL2832U-based DVB-T dongles
- RTL-SDR from http://cgit.osmocom.org/cgit/rtl-sdr/


2. Installation

Get the latest code from: https://github.com/n1gp/rtl_hpsdr

The Makefile is setup to detect the CPU NEON or SSE2
SIMD capabilities. If none are found it will compile
without optimizations for the downsampling routines.

$ make

3. Usage

rtl_hpsdr can be started using command line options or with a
confuration file. See rtl_hpsdr.conf for an example.

$ ./rtl_hpsdr -c rtl_hpsdr.conf

For help

$ ./rtl_hpsdr -h

4. Known problems

- This server program needs to be run on a separate PC than
  the client program. Probably due to improper network settings
  in the reveal and discovery socket layers or perhaps its not
  possible to connect from the same client port to the same
  server (address and port). [ FIXED in version 1.3 ]

- Periodically the Alsa local sound skips and is caused by xruns.
  Possibly due to improper period and buffer settings.

- The down sampling routines have not been validated for accuracy
  and perhaps could be better optimized.

5. Credits and License

rtl_hpsdr is designed and written by Richard Koch N1GP,
and is licensed under the GNU General Public License.

I give thanks and credit to the http://openhpsdr.org community.
All the folks who made the rtl-sdr libraries and utilities.
The work of John Melton, G0ORX/N6LYT and others on
the ghpsdr3 open source projects which provided many examples
for communicating with HPSDR. Some alsa audio routines
I borrowed from Matthieu Sozeau and the XMMS project. Also
Olli Parviainen and his application SoundTouch where I got idea's
on optimizing the downsampling filter routines using SIMD
instructions, http://www.surina.net/soundtouch

#RTL devices on USB hub to get full power
ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="0bda", ATTR{idProduct}=="2838", ATTR{bConfigurationValue}!="1", ATTR{bConfigurationValue}="1", RUN+="/bin/bash -c 'echo 1 > /sys/bus/usb/devices/%b/bConfigurationValue'"