The Internet Radio Linking Project. Presentation for the Triangle Linux Users Group by Jim Price WW4M April 10, 2003. Portions of this presentation courtesy of KD4RAA, VE3SY, VE7LTD, VK3JED. Overview. What is Amateur Radio? Ham Radio Activities IT and Amateur Radio
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Presentation for the Triangle Linux Users Groupby Jim Price WW4M
April 10, 2003
Portions of this presentation courtesy of KD4RAA, VE3SY, VE7LTD, VK3JED
Entertainers: Chet Atkins WA4CZD, Ronnie Milsap WB4KCG, Marlon Brando FO5GJ, Patty Loveless KD4WUJ, Gary Shandling KD6OY, Burl Ives KA6HVA, Arthur Godfrey K4LIB, Priscilla Presley N6YOS
Joe Walsh WB6ACU
.A huge number of politicians and royals including:Gov. George Pataki N2ZCZ, Sen. Barry Goldwater K7UGA, Spain’s King Juan Carlos EA0JC, Jordan's King Hussein JY1 and Queen Noor JY2, Argentina’s Pres. Carlos Menem LU1SM, India’s Rajiv Gandhi VU2RG
Famous and infamous hams: most astronauts, Hugh Downs KD6WUS, Art Bell W6OBB, Kevin Mitnick N6NHG, and the author of The Joy of Sex, Dr. Alex Comfort KA6UXR
Walter Cronkite KB2GSD
Radio or Repeater
Distant Radio or Repeater
PC -or- Radio Access:
Created by Dave Cameron VE7LTD of Vancouver, BC
Dave was frustrated with the unreliable operation of Windows-based Iphone and turned to linux.
Iphone and other systems use VOX. IRLP uses COS.IRLP is radio-access only.
November 1998 - 2
December 1999 +10= 12June 2000 +20 = 32December 2000 +29 = 61June 2001 +61 = 122December 2001 + 199 = 321June 2002 + 236 = 557December 2002 +263 = 820
database records 1/1/03
445 United States154 Canada
54 Australia + New Zealand
12 Caribbean + Bermuda 6 Japan
3 Southern Africa
2 Ecuador, Mexico
active nodes 4/1/03
Speak Freely for linux is Open Source, while Speak Freely for Windows is GPL.
Linux offered the best in reliability, programmability, efficiency, and functionality.
IRLP currently ships with RH 7.3 and will run on a 486 DX100 or better computer(init=3).
Custom IRLP Software
IRLP Control Board
Does COS, PTT & DTMF
DB9 IRLP to Radio Interface
LPT1 to IRLP Jumper Cable
DB25 for Data Control from LPT1 & IRLP
+12VDC from PC
v.2 IRLP card
– DTMF Decode Sense – Carrier Operated Squelch Sense
– PTT out to Link Radio or Controller
10MB HubLinksys Router
DualBand 2M/440Control Xcvr
KD4RAANode 4260 / 4270Configuration
4270 Link Radio 4260 Link Radio
Audio Equalizer and Broadcast Leveling
Notes from Dave Cameron, VE7LTD
Audio streaming is enabled when the link radio receives a signal with COS and keys the IRLP interface card.
The sound card receives the radio’s audio and creates a continuous mono 8-bit digital stream of raw audio at 8000Hz (64k bps).
Speak Freely’s sfmike program compresses the audio stream by a factor of two (32k bps) using an audio compression algorithm (codec).
The audio is split into packets, which are transmitted over port 2074 using a User Datagram Protocol (UDP) stream. UDP does NOT confirm the reception of packets - it "fires and forgets"
Speak Freely’s sfspeaker receives the packets on port 2075 and rejoins them into an 8-bit ULAW stream.
Next the ULAW stream is uncompressed back into an 8-bit raw stream of audio.
The raw audio is streamed through the digital to analog (D/A) converter (the output device of your sound card).
The IRLP interface card keys the radio when the audio stream is present (live -- no buffering).
Jason Woodard, http://www-mobile.ecs.soton.ac.uk/speech_codecs/
ADPCM quantizes the difference between the sampled signal and a prediction. If the prediction is accurate, the difference between the real and predicted samples will have a lower variance than the real speech samples and will be accurately quantized with fewer bits than needed for the original.
At the decoder the quantized difference signal is added to the predicted signal to give the reconstructed speech signal. Performance is aided by using adaptive prediction and quantization, so that the predictor and difference quantizer adapt to the changing characteristics of the sampled speech.
GSM uses a Regular Pulse Excited (RPE) codec. Input is split into 20ms frames, each with 8 short term predictor coeffiecients. Frames are further split into four 5ms sub-frames, each with a delay and gain for a long term predictor. After short and long term filtering, the residual signal for each sub-frame is decimated into three possible excitation sequences, each 13 samples long. The sequence with the highest energy is chosen as the best rep-resentation of the excitation sequence, and each pulse in the sequence has its amplitude quantized with three bits.
At the decoder the reconstructed excitation signal is fed through the long term and short term synthesis filters to reconstruct the speech. A postfilter improves perceptual quality
2074 - 2093 Audio (bi-directional UDP)
15425-7 IRLP Control/Update (TCP)
Outbound ports used: 80 (http) for updates
873 or 8873 (rsync) for downloading updates
10000 (for IP determination)
parallel port set to "standard" or "compatible" mode, not to ECP, EPP or bi-directional
512-bit bi-directional PGP authentication ensures connections only with other IRLP nodes.
Redundant servers support IRLP-BIND(DHCP isn’t a problem) as well as download of pgp key rings, software updates, and station ID wavfiles.
IRLP accepts commands from keyboard or via DTMF (dual tone multi frequency, i.e. “Touchtones”)
“I had released code under the GPL, and it led to nothing but 1000's of emails criticising my code, asking for features, wondering why I built this that way, etc... I got tired of answering questions.”
“There is a strong commercial potential for this product, and I did not want to hand several 1000 hours worth of code to the private sector just to be replicated.”
“Closed code maintains a standard, which open releases would compromise.”
Reflectors(like chat rooms -- multiple nodes connected together, hearing audio from one node at a time)
Established for coordinated response to severe weather events and for public service
Links NC repeaters beyond the range of conventional RF linking systems
During Hurricane Lily, linked stations in Louisiana with the NationalHurricane Center in Florida
Has linked stations from Georgia to Maryland to track several winter storms
Simulcast a ham radio contact between the International Space Station and Chapel Hill middle school students
Participated in the Boy Scouts’ JOTA event