ENIGMA 2000 Newsletter - Issue 16

May 2003
Articles, newsreports and Items of interest :enigma2000-owner@yahoogroups.com

Beginners' corner

We return again with the prediction charts, provided by GD, that are proving of great help to newcomers. Where a "possible sked" is indicated please highlight these in your logs if heard, it allows us to update our info more quickly and GD of the CW Desk is always hungry for information.

M13 Prediction Chart May 2003:

Day	Dates		Time	Freq	ID	S	Notes
Th	1	15	2000	12834	253	227
Th	1	15	2145	8183+	757	249
Th	1	15	2200	5119?	186	238	G22	Possible sked
F	2	16	0400	7994+	284	224
F	2	16	2000	12834	253	227
F	2	16	2000	8497	284	224
F	2	16	2145	8183+	757	249
S	3	17	0230	6715	767D	278?
S	3	17	0300	6212+-	378	259
S	3	17	0400	7994+	284	224
S	3	17	0430	5788	411	249
S	3	17	2000	8497	284	224
S	3	17	2030	5788	411	249
S	3	17	2100	5757	378	259
Su	4	18	0230	6715	767D	278?
Su	4	18	0430	5788	411	249
Su	4	18	19/20	13415	261	268
Su	4	18	2000	5315	123	???		Possible sked
Su	4	18	2030	5788	411	249
M	5	19	0300	6212+-	378	259
M	5	19	0330	11475	458	224
M	5	19	19/20	10246	261	268
M	5	19	19/20	11306	517	229
M	5	19	2100	5757	378	259
M	5	19	2110	Srch 4/6	427	???
M	5	19	2120	9926	746	229
M	5	19	2200	12216	458	224
T	6	20	0330	11475	458	224
T	6	20	0600	Srch 6/9	572	224
T			19/20		517	229
T	6	20	2100	8932	272	268
T		20	2100	5376	346	222		Possible sked
T	6	20	2200	12216	458	224
W	7	21	0300	7854+-	254	234
W	7	21	0600	9094	823	224
W	7	21	0630	10887+	474	224
W	7	21	2100	7517	254	234
W	7	21	2100	5085	367C	226
W		21	2100	5376	346	222		Possible sked
Th	8	22	0300	7854+-	254	234
Th	8	22	0600	9094	823	224
Th	8	22	0630	10887+	474	224
Th	8	22	15/17	9965	865	224
Th	8	22	2000	12714	714	224
Th	8	22	2100	7517	254	234
Th	8	22	2100	5085	367C	226
Th	8	22	2200	5119?	186	238	G22
F	9	23	15/17	9965	865	224
F	9	23	2000	12714	714	224
F	9	23	2000	5315	123	???		Possible sked
S	10	24	0230	6715	767D	278?
S	10	24	2100	4732	764B	272
Su	11	25	0230	6715	767D	278?
Su	11	25	1900	8086	417	224
Su	11	25	2100	4734	764B	272
Su	11	25	2115	8067+-	501	228
M	12	26	0300	8247+-	???A	231
M	12	26	1900	8086	417	224
M	12	26	2000	9945	372A	231
M	12	26	2115	8067+-	501	228
T	13	27	0300	8247+-	???A	231
T	13	27	0600	Srch 5/9	572	224
T	13	27	0900	7678	679	240		Possible sked
T	13	27	1900	7698	679	240		Possible sked
T	13	27	2000	9945	372A	231
T		27	2100	5376	346	222		Possible sked
T		13	2145	3868?	342	237	S04
W	14	28	0900	7678	679	240		Possible sked
W	14	28	1900	7698	679	240		Possible sked
W		28	2100	5376	346	222		Possible sked
W		14	2100	????	269	191	E18	Possible 2145
Th		15	2100	????	269	191	E18	Possible 2145

XP's (Polytone) Notes

Since the early days of the E2K Newsletter there have been numbers of comments/questions regarding the reception/interpretation of the Polytone systems group (XP, XPL, XPM, XPH) as referred to in the ENIGMA Control List.

[ See also article regarding XPL in this issue, it's proving to be a different system altogether]

These comments were along the lines of :-

How do I know if I'm correctly tuned ?
How do you establish the tonal freqs ?
How do you work out what the tones represent ?
The tones I hear are different to the published .wav/mp3 samples

Although E2K were already carrying out intensive analysis of the XP's the combined comments set us thinking about our approach to the problem, and it was evident that certain "protocols" needed to be implemented to resolve the issues raised.

Important amongst these were :-

Establishing a Reference Datum for each system.
Referencing the Datum to a known, dependable "master" signal.
Allowing for equipment variations/errors.
Allowing for human tonal perceptions
Having a "commonality" across all systems, if possible
Using common analysis & recording programmes

The "master" signal was relatively easy, we used Standard Time Signals, where all the parameters are known, accurate and repeatable. The chosen "datum's" were referenced to these sigs in the analysis programme.

Common programmes, we decided on Cool Edit for recording / signal manipulation and Spectogram for the analysis, both are widely used in the hobby and are accurate and flexible.

Human tonal perception basically has to be ignored, the variations are too great. In a quick "experiment" 2 groups of 5 "volunteers" at my workplace were played a series of tones from 200 - 2500Hz , in random order, and asked to give a independent written opinion, in tick boxes, as to whether each tone was Low/Medium/High. There were 10 differing answers !!!.

Equipment variation/errors. We all like to think that "our" kit is perfect - far from it, but amply good enough for most purposes. A check of manufacturers specifications, in the mid-price range of the typical kit we use, showed that almost all quoted an accuracy of =<50Hz of the displayed freq and that there was no "standard" offset for SSB and the crystal ageing figures were relatively high. Together these cumulative errors could make a difference large enough for a "perceptive miss-identification" but my own listening interests gave a "cheep & cheerful" answer that is easy to use and remarkably accurate in checking receiver calibration.

[ Install the shareware version of Charles Brains' PC-HFDL prog, even if you have no interest in aircraft monitoring. The accuracy of the TX's and the algorithms Charles uses will give a readout correct to 6 decimal places of the variation from the displayed freq, but always use the Base Station TX's, sent every 32 seconds, and not the aircraft ones. There are many HFDL TX,s spread from 3 -22MHz, we can supply a chart on request.]

Reference Datum's & Commonality combined were the most difficult to reconcile but it was noticed that XP & XPH, and presumably the new XPM, all have a "space" character which occurs numerous times in every TX as being a common factor.

The tone of this "space" is now used as the Datum for our analysis, they are for XP 303Hz & XPH 1304Hz +-3HZ, XPM still being assessed. Recordings from differing sources can now easily have an "error correction" applied by measuring the variation of the "space" tone from the Datum and applying the same figure to "adjust" all other tones.

And the last, but important, point - how can one easily identify each system for logging purposes?

It's easy without even knowing what the specific tones are, a Spectogram plot will show [as you will read later] :-

XP uses 14 tones
XPM uses 18 tones
XPH uses 13 tones