By Alex Harker
https://github.com/HISSTools/HISSTools_Impulse_Response_Toolbox
Also check out the complete set of HISSTools. With convolution, sample accurate timing, granular synthesis, and more.
http://www.alexanderjharker.co.uk/Software.html
How to use Java with Eclipse & Max6
RTTY at 300+ bps in Max
notes
After a few vexing timing issues I have been able to send and decode RTTY (technically AFSK audio frequency shift keying ) in Max at 300 baud. Click hear to listen to an example of a 13 word message at 300 bps (300 baud)
The js object adds significant delays (on the order of a few milliseconds) – so I replaced the encoder with a coll and that cleaned up the timing problems when encoding. This patch demonstrates the issue:
Also… You can use threshold~ instead of snapshot~to feed binary pulse amplitude detection logic into edge~ – but you need to run the signal through average~ to prevent the amplitude from repeatedly dropping to zero at the signal frequency. Like this:
Is it better than snapshot~? it seems to be, but who knows – at these speeds it would probably be better to write the whole thing in gen~
There are a few other things – like using counter~ instead of phasor~ to drive the decoder clock. This allows you to restart the clock, when the onset of the start bit is detected – and you can add a variable amount of delay to find optimal point in the signal vector to read the pulse. At 300 bps, at 96k SR, each pulse is 320 samples (3.1 milliseconds) –
I’ll write more on this later –
The Katja Vetter article on Beat-Slicing was helpful – along with several Max tutorials on Audio control rates, and envelope followers.
Local Patches are in;
tkzic/ max teaching examples/
- rtty-send10.maxpat
- rtty-recv9a.maxpat
Digital PLL with gen~
Inspiration for the PLL fm detector in gen~
by SKRASMS at Cycling 74 Forums
http://cycling74.com/forums/topic/sharing-digital-pll-made-with-gen/
Max potpourri externals
By Eric Lyon
Have been relocated to:
https://github.com/ericlyon/LyonPotpourri-MaxMSP
Object Listing: - adsr~ a simple ADSR envelope that can be click triggered - arrayfilt~ fft-based filtering by drawing into an array - bashfest~ a click driven buffer player with randomized DSP - buffet~ provides operations on a stored buffer - bvplay~ selective playback from a stored buffer with enveloping and increment control - cartopol~ convert a spectral frame from cartesian to polar form - channel~ access to a precise address in the signal vector - chopper~ munging loop playback from a buffer - clean_selector~ like selector~ but crossfades when switching channels - click~ converts a bang to a click - click2float~ translates a signal click to a float message - clickhold~ sample and hold a click - convolver~ non-real-time convolution with impulses of arbitrary size - distortion~ lookup function distortion - dmach~ pattern based sample accurate drum machine prototype - expflam~ converts a click to an exponential flam click pattern - flanjah~ simple flanger - function~ write various functions into an array - granola~ granular pitch scaling - granulesf~ granular synthesis module reading from a soundfile in a buffer - granule~ granular synthesis module reading from a stored waveform in a buffer - greater~ compares two signals on a per-sample basis - kbuffer~ low sampling rate buffer to capture gestures - killdc~ DC block filter - latch~ sustain an incoming click with sample-accurate timing - magfreq_analysis~ transforms a time domain signal to a magnitude/frequency spectrum - markov~ implements a first order Markov chain - mask~ a click driven pattern sequencer - npan~ power-panning to an arbitrary number of output channels - oscil~ oscillator with flexible waveform specification - phasemod~ phase modulated waveform - player~ click driven buffer player that can sustain multiple iterations - poltocar~ convert spectral frame from polar to complex representation - pulser~ pulse wave generated by additive synthesis - quadpan~ pan an incoming sound within a quadraphonic plane - rotapan~ rotate an array of input channels to the same number of output channels - rtrig~ generates random click triggers - samm~ sample accurate multiple metronomes, with click signal articulation - sarec~ sample accurate recording - sel~ sample-accurate implementation of the sel algorithm - shoehorn~ collapse from a larger number to a smaller number of audio channels - sigseq~ signal level numerical sequencer - splitbank~ - split an incoming sound into complementary, independently tunable spectra - splitspec~ split an incoming sound into complementary spectra - squash~ implementation of a compression algorithm by Chris Penrose - stutter~ stuttering playback from an array - vdb~ a delay line using an array for storage (no vector limit on feedback delaytime) - vdp~ a simple, self-contained delay unit - vecdex~ outputs the sample index within the current signal vector - waveshape~ a Chebychev function lookup waveshaper - windowvec~ apply a Hann window to the input signal vector
Max debouncer
Here is a patch – we need to convert to Pd
decoding RTTY in Max
Using a local clock
(update 12/18/2013) Here is a video that shows acoustic coupling between to computers running RTTY in Max at 12.5 bits/second
Next version will have better syncing within the patch (i.e.., sample accurate timing, instead of [metro], [delay], and [snapshot]
original post
Have added stop and start bits to ascii rtty signal and reversed mark and space to the normal setting.
The current local test patches are:
tkzic/max teaching examples/
- rtty-sim7.maxpat
- rtty-recv7.maxpat
Accurate communication only works at very low speeds – around 11 bits/sec. The timing on the receive side is very critical. The way it works now, is that it uses the first start bit, after a period of inactivity, to reset the clock. The ‘delay’ setting for the clock seems to be the key factor in whether the bits get read as characters.
I think that any speed increases at this point will require sample accurate timing on both send and receive sides. But as a proof of concept we have a decent start. Its also possible that the filtering/bit detecting could be improved – but again, this is a matter now of precise timing adjustments at the sample level – and using more frequent and accurate clock adjustments on the receive side to maintain sync.
Max audio-rate sequencing
Signals, for more accurate timing
from cycling74.com
http://cycling74.com/wiki/index.php?title=MSP_Sequencing_Tutorial_1:_Audio-Rate_Sequencing
RTTY encoding and decoding in Max
notes
Today I was able to get an AFSK (audio frequency shift keying) system running in Max – sort of – It encodes text into ASCII bits and decodes the signal back into text – with a clock set at around 30ms (32 bits/second) – but there is no clock synchronization yet. Or stop bits, etc., The patch just uses the transmitter clock to sync the receiver (cheating)
Listen to an example of the word ‘hello’ at 32 bits/sec
local file is in max teaching examples/rtty-sim5.maxpat
Next step will be to get receiver sync happening – then make it conform to RTTY standard – probably a few days effort for this, but at least this is a proof of concept.
The synchronization may need to happen at the sample level (gen~) because it requires finding the beginning and end of bits – in order to set the clock pulses accurately.
Crash report
How to find a Mac OS crash report for Max
By Sam at Cycling 74
“You just need to open Console, disclose ~/Library/Logs, disclose DiagnosticReports, right click on the crash report from Max and click Reveal in Finder.”
