WSPR - The network
The Weak Signal Propagation Reporter Network is a group of amateur radio operators using K1JT's MEPT_JT digital mode to probe radio frequency propagation conditions using very low power (QRP/QRPp) transmissions. The data collected are available to the public.
The WSPRnet web site provides a simple user interface for querying the database, a mapping facility, and many other features.

WSPR 2.0 - The program
WSPR (pronounced "whisper") stands for "Weak Signal Propagation Reporter".
The WSPR software is designed by Joe Taylor ( K1JT ) for probing potential radio propagation paths using low-power beacon-like transmissions. WSPR signals convey a callsign, Maidenhead grid locator, and power level using a compressed data format with strong forward error correction and narrow-band 4-FSK modulation. The protocol is effective at signal-to-noise ratios as low as -28 dB in a 2500 Hz bandwidth. Receiving stations with internet access may automatically upload reception reports to a central database - WSPRnet.

WSPR The protocol

Specifications of the WSPR Protocol
Standard message	callsign + 4-digit locator + transmitted power level [dBm]
Standard message components after lossless compression	28 bits for callsign, 15 for locator, 7 for power level, 50 bits total
Forward error correction (FEC)	convolutional code with constraint length K=32, rate r=1/2
Keying rate	1.4648 baud
Number of binary channel symbols	162
Modulation	continuous phase 4-FSK, tone separation 1.4648 Hz
Occupied bandwidth	about 6Hz
Synchronization	162-bit pseudo-random sync vector
Data structure	each channel symbol conveys one sync bit (LSB) and one data bit (MSB)
Duration of transmission	110.6 s
Minimum S/N for reception	around -28 dB on the WSJT scale (2500 Hz reference bandwidth).

Specifications of the LZ0DLS
WSPR message	LZ0DLS KN12 10 Source-encoded message (50 bits, hex): 94 7B 7B 86 EB 92 80 Data symbols: 1 1 0 0 1 0 0 0 0 0 0 0 1 0 0 0 1 0 1 1 0 0 0 1 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 0 1 1 1 1 1 0 0 0 1 1 0 0 1 0 0 1 0 1 1 1 1 1 1 0 0 0 0 0 1 1 0 1 0 1 1 1 0 1 0 0 1 0 0 1 0 1 0 0 0 0 1 1 1 1 1 1 1 0 1 0 0 0 0 0 1 0 1 0 0 0 0 1 1 1 0 0 0 0 0 1 1 1 1 1 1 0 0 0 1 0 0 1 1 1 0 1 1 0 1 0 0 1 0 1 1 0 0 0 0 0 1 0 0 1 1 0 0 1 1 1 0 0 Sync symbols: 1 1 0 0 0 0 0 0 1 0 0 0 1 1 1 0 0 0 1 0 0 1 0 1 1 1 1 0 0 0 0 0 0 0 1 0 0 1 0 1 0 0 0 0 0 0 1 0 1 1 0 0 1 1 0 1 0 0 0 1 1 0 1 0 0 0 0 1 1 0 1 0 1 0 1 0 1 0 0 1 0 0 1 0 1 1 0 0 0 1 1 0 1 0 1 0 0 0 1 0 0 0 0 0 1 0 0 1 0 0 1 1 1 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 0 0 0 0 1 0 1 0 0 1 1 0 0 0 0 0 0 0 1 1 0 1 0 1 1 0 0 0 1 1 0 0 0 Channel symbols: 3 3 0 0 2 0 0 0 1 0 0 0 3 1 1 0 2 0 3 2 0 1 0 3 3 3 1 2 2 2 0 2 2 0 3 2 2 3 2 1 2 2 2 2 2 0 1 0 3 3 0 0 3 1 0 3 0 2 2 3 3 2 3 0 0 0 0 1 3 2 1 2 1 2 3 2 1 2 0 1 2 0 1 2 1 3 0 0 0 1 3 2 3 2 3 2 2 0 3 0 0 0 0 0 3 0 2 1 0 0 1 3 3 2 1 1 0 0 1 3 2 3 2 2 2 1 1 1 2 0 0 2 2 3 0 3 2 0 3 1 0 2 0 2 2 0 0 1 1 0 3 0 1 3 2 0 0 3 3 2 0 0
CW ID	LZ0DLS WSPR BEACON KN12PQ 600 ASL
Operating Frequency :	10.140 240 MHz
Power supply :	200mA @ 12V
Power :	actual: 10 mW ( 10dBm ) / planned: 5 W ( 37dBm )
Coordinates:	23 15' 26"E; 42 41' 11" N

Beacon Hardware

• The Core:
  • Silicon Labs Si570 CAC000141DG DCO. Decode chip's part number
  • Seeduino (v2.12) - Atmel MCU ATmega168 based board
• Time refference: cheap GPS Receiver Module by Rockwell (thanks to eBay :-) ) + external antenna
• Power Amplifier - (planned) 2SC1970(driver) + IRF510 (final stage)
  The design of the amplifier is borrowed from: HF SDR Transceiver-AVALA-01 by YU1LM
  similar solutions:
  • Mighty Mike TX by by N1HFX
  • The NB6M Miniboots
  • Двудиапазонен CW/SSB трансивър
• Antenna - I dont know yet!?

The beacon firmware is coded in C language, using Arduino 0022 IDE (will be posted later)

Why DLS ? The suffix of the callsign stands for "Dobrata Lamya Spaska". Translated in english - Pretty dragon Spaska :-)
Female dragon Spaska is a mythical hero of Bulgarian fairy tales and also involved in many jokes of recent times. She is good at heart and LZ0DLS just whispers her name instead of roaring and scaring people. :-)

Step-By-Step:
2 Nov 2011 Request for LZ0DLS's license was send to Communications Regulation Commission (CRC)

3 Nov 2011 First WSPR message was transmitted (5 mW), received at the opposite side of my desk and successfully decoded. Transmissions nominally start one second into an even UTC minute: i.e., at hh:00:01 , hh:02:01 During first tests start/stop timing - by hands :-). Data symbols, Sync symbols and resulting Channel symbols were calculated by WSPRcode.exe

4 Nov 2011 Frequency adjustment procedure. Finding the correct setting for Si570 parameters is very well described by Thomas MARTIN DF7TV's notes on SI570/PICAXE experiments But in my case there was no need to measure Fstart. I just measured output frequecy from Si570 using FT897D after warm-up. The signal was about 1 kHz higher than expected - I just recalculated register 7 to 12 values to reduce the frequency to the desired value. The step between channel frequencies (tone separation) 1,4648 Hz (0x673). Calculations were done by Silicon Labs Programmable Oscillator Software

5 Nov 2011 LZ0DLS learned Morse code and now it can send CW ID (as required by regulations for amateur radio service in our country)

6 Nov 2011 LZ0DLS now listens for GPS satellites to set its clock. GPS Module Rockwell

11 Nov 2011 National regulator - Communications Regulation Commission (CRC) issued LZ0DLS's licence

12 Nov 2011 First "on-air" tests
15 Nov 2011 5 Watts PA (2SC1970 + IRF510) is ready to be tuned and tested. Does it work? I don't know yet....

19-20 Nov 2011 Too busy - LZ DX Contest this weekend :-)
....... etc.....etc.....etc

19 Jan 2012 Two months later... PA is still not ready ... so LZ0DLS started at 10mW.
"weak signal" means - weak signal :-)
First spots >>>

Unique reporters, ordered by distance >>>