Radio Timings

[John Gibbons]

All,

Just a quick summary of some radio testing I did because the opportunity presented itself.

John N8OBJ

John C. Gibbons

Director - Sears Undergraduate Design Laboratory

Dept. of Electrical Engineering and Computer Science

Case Western Reserve University 

10900 Euclid Ave, Glennan 321

Cleveland, Ohio  44106-7071
Phone (216) 368-2816 FAX (216) 368-6888
E-mail: jc...@case.edu

[Steve Cerwin]

Very Nice John. Excellent write up. Your traces are really clean and unambiguous. Well done! To add more benchmarks, similar testing here pegged the delay through my IC-7610 at 4.0 mS (same as yours) and the R8600 at 12.0 mS in AM mode. Additionally, the delay through the R8600 was mode dependent. 

TWO FULL SECONDS THROUGH THE KIWI!!!!!! Holy lethargy Batman! What do they do - send it to Japan for processing? The trick of summing a little of the 1 pps pulse directly into the RF input may be a viable option here. Then the timing reference and signal you are copying at least go through the receiver delay together. Just edge differentiating the leading edge through a small capacitor worked well here at 2.5 and 5 MHz but not so well at 15 MHz. But using the 1 pps pulse to trigger an on-frequency RF burst out of the function generator to get a wider pulse worked great. A 350 uS pulse width made a hump about as wide as a half cycle of the WWV timing tick and was very recognizable. It made TOF measurements easy just using a .wav file recorder. 

73, Steve

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<RadioDelayTesting.pdf>

[Gary Mikitin]

Well done, John.  Perhaps “Rx Delay” will become a KPI (Key Performance Indicator) in future rig reviews in the amateur literature.

It has been said that receiver performance has benefitted greatly from increased scrutiny.  Transmitter cleanliness is (hopefully) the next area of focus.  While the average SSB or CW operator wouldn’t notice the difference, with the digital modes continually becoming more sophisticated, minimizing Rx delay could yield competitive advantages.