[600MRG] 630m ground-wave testing - we need more than anecdotal comments

[Ralph Wallio, W0RPK]

Anecdotal comments by 630m experiment participants will have very little 
impact on emergency communications planning by ARRL Amateur Radio 
Emergency Service leaders.  They will need fully documented results from 
numerous expertly designed and executed 630m ground-wave propagation 
experiments. During my reign of terror as a former ARES EC, then DEC, 
then SEC for ARRL's Iowa Section, I would not have considered applying a 
radio communications band and propagation based solely on anecdotal 
comments. However, if we go to the effort to prove the reliability of 
630m ground-wave coverage, current ARES leaders will seriously consider 
applying it for regional emergency communications.

Our ARRL 500kc Experiment coordinator Fritz Raab, W1FR, documented early 
630m ground-wave experiments in his paper, "Tests of ground-wave 
communication at 500 kHz during winter 2010 - spring 2011", which is 
available via http://500kc.com/downloads/RN11-16.pdf. Tests in the 
upper-Midwest used WSPR to understand midday ground-wave SNR performance 
and then repeated digital transmissions to gather character-error-rate 
performance for digital modes allowed to WD2XSH licensees.  The transmit 
station for these tests was designed for portable operation, see 
http://showcase.netins.net/web/wallio/WD2XSH-34.htm.

Interesting additional findings from these tests included, first, 
extensive and precision testing between WD2XSH/34 and John Fickes, 
KC0BMF, a ~20-mile path, used WSPR and digital modes to find required 
SNR for acceptable character-error-rates.  Performance of modes BPSK31, 
requiring -11dBsnr, and BPSK10, requiring -17dBsnr, was found to be very 
close to that given by MultiPSK author F6CTE in his very extensive 
Handbook.  These testing methods need to be extended to other digital 
modes, especially those with forward-error-correction.  See John 
Andrew's, W1TAG, extensive discussion via 
http://www.w1tag.com/600M_Modes.htm.

Second, Chris Sparks, KC0TKS, used WSPR data via our 190-mile 630m 
ground-wave path to understand how E-Probe receive antenna reception 
improves when height is above all close residential structures.  His 
630m WSPR performance improved 5dB when Chris increased height of his 
DIY PA0RDT E-Probe antenna from 10ft to 20ft AGL.  The magnitude of this 
improvement needs further testing and documentation by others.  (My 
reception in Iowa of WD2XSH/20 back during September 2006 using my 
minimal DIY E-probe antenna --- inside our garage with significant 
signal loss --- is a testament to the high quality of Rudy's early 630m 
station.)

TNX es 73 de Ralph Wallio, W0RPK
http://showcase.netins.net/web/wallio/