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author | Matthias P. Braendli <matthias.braendli@mpb.li> | 2014-02-07 09:24:39 +0100 |
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committer | Matthias P. Braendli <matthias.braendli@mpb.li> | 2014-02-07 09:24:39 +0100 |
commit | 05bc267d10902357814a8493f18937f5cb51f8f6 (patch) | |
tree | cd045bb0a708d64a3161968a54d8d6cb46b6a43e /README-SFN | |
parent | dcf1a7527bf3ea977710eae30bd24d8c65c9d6c5 (diff) | |
download | mmbtools-aux-05bc267d10902357814a8493f18937f5cb51f8f6.tar.gz mmbtools-aux-05bc267d10902357814a8493f18937f5cb51f8f6.tar.bz2 mmbtools-aux-05bc267d10902357814a8493f18937f5cb51f8f6.zip |
some updates, removal of old scripts
Diffstat (limited to 'README-SFN')
-rw-r--r-- | README-SFN | 127 |
1 files changed, 0 insertions, 127 deletions
diff --git a/README-SFN b/README-SFN deleted file mode 100644 index de4ef7c..0000000 --- a/README-SFN +++ /dev/null @@ -1,127 +0,0 @@ -README for the SFN patch -======================== - -Concept -------- - -Each modulator receives ETI frames with absolute timestamps. These timestamps -are composed of two parts: -- The TIST field as defined in the ETI standard, giving an offset after the - pulse per second signal; -- A time information transmitted using the MNSC, representing the precise time - when the frame must be transmitted, with one-second resolution. - -When CRC-DABMUX is called with -s, the TIST is defined in each frame. The -Time is always encoded in the MNSC. - -In a SFN setup, it is not possible to rely on a modulator to slow down the -Ensemble multiplexer. CRC-DABMUX takes an additional parameter -r to output one -ETI frame every 24ms. This output parameter only adds a simul:// output. - -The ETI stream must then be made available to several transmission sites. For -this, the eti_tcp server can be used. -The eti_tcp server listens on the port specified on the command line. -An example invocation is: -./mux-throttled.sh -s -m 1 | ./eti_tcp/eti_tcp.py 54001 - -Each modulator then receives the ETI stream through a TCP connection. Each frame -contains the complete timestamp, to which an per-modulator offset is added. -The sum is then given to the USRP. The offset can be specified in two ways: - -using -o delay: -Adds a constant delay specified on the command line (see 1st example). - -using -O delayfile -Adds the delay specified in the given file. The file must contains a single -line containing a floating point number. This file is read each 50 frames, and -the modulator delay is updated. - -In both cases, the units are seconds. - -Example modulator invocation (for a B100 USRP supporting 2048Msps and with a -fixed delay of 2.3 seconds) -nc localhost 54001 | ./moduhd-2048.sh -o 2.3 - -Example modulator invocation (for an USRP requiring resampling and with a delay -specified in a separate file "moddelay") -nc localhost 54001 | ./moduhd-resample.sh -O moddelay -G 5 - -It is also possible to set daugherboard gain using -G. Furthermore, the transmission -frequency is set on the command line, as seen in the examples in moduhd-XXX.sh. - -CRC-DABMOD uses the UHD library to output modulated samples to the USRP device. -When started, it defines the USRP time using the local time and the PPS signal. -It is therefore important to synchronise computer time using NTPd. - -When a frame arrives with a timestamp that is in the past, the frame is dropped. -If the timestamp is too far in the future, the output module waits a short -delay. - -Synchonisation can be verified by using an oscilloscope and a receiver. It is -very easy to see if the null symbols align. - - -Hardware requirements ---------------------- - -The following hardware is required to test the SFN patch to the CRC mmbTools: -- Two USRPs ; -- One or two computers with the mmbTools installed ; -- A network connection between the two computers ; -- A 10MHz refclk source ; -- A 1PPS source synchronised to the 10MHz ; -- An oscilloscope to check synchronisation. - -The lab setup used in the experiments : -http://pic.mpb.li/IMAG0411.jpg - -In this example, one USRP B100 and one USRP2 are used. Modulation is done on two -different computers, but it also works with a single computer. In that case, the -device string for the -u option for CRC-DABMOD must specify the device. (e.g. --u "type=b100", -u "type=usrp2" or -u "serial=ABC123") - -The HP33120A generator at the bottom is used to generate the 10MHz REFCLK (sine, -2Vpp). It's sync output is used as 10MHz IN for the Agilent 33250A generator. -The Agilent is set to a square wave, 1Hz. Its sync output is then wired to the -PPS input of the USRPs. - -List of changes made --------------------- -To CRC-DABMUX: -- Throttled output option instanciates a simul output -- Set TIST and use MNSC to transmit time -- Command line arguments handling - -Files: -Modified Eti.h and DabMux.cpp - -To CRC-DABMOD: -- Added multithreaded UHD Output module -- Added normalisation for UHD (we must divide output samples by - 32768.0) -- Command line arguments handling -- Changed the flowgraph to be able to chose between outputs -- Added decoding of time in MNSC -- Added delay control for the modulator using -o and -O -- Initially set the timezone to UTC, because the MNSC is in UTC - -Files: -Added OutputUHDThreaded.{cpp,h}, TimestampDecoder.{cpp,h}; Modified DabMod.cpp, -DabModulator.h, Eti.h, EtiReader.{cpp,h}; Changed some .h files to include -<stdio.h> because of compilation issues; Corrected OutputMemory char* name(). - - -Future elements to be changed ------------------------------ -- Communicate delay and buffer information between multiplexer and modulators, - to have a better control about delays. -- Handle UHD asynchronous messages in another thread, and use this information - for monitoring - -Repository: -http://hg.mpb.li/mmbtools-sfn/ - -2012-07-11 -Matthias P. Braendli -matthias@mpb.li - |