10
APPENDIX I.
METHOD OF CONDUCTING TRIALS,
An aerial consisting of four single wires was used, and a switch inside the office enabled this aerial to be connected rapidly to any one of the three sete under test or to the set used for ordinary communication. The sets were given tests in turn, changing each 4-hour watch. As soon as the test "Longs were heard to commence the G.P.O. set was connected to aerial. When it worked, one of the remaining two sets was connected up, and after that had worked the last set was tested. If time did not allow of both the 4-second dash sets being tested, the one that missed was taken first at the next test. The G.P.O.
set was therefore in a position to get a rather greater number of tests than the other two.
HOME WATERS TRIAL.
11
APPENDIX II.
FOREIGN WATERS TRIAL.-OUTWARD VOYAGE.
Both sets were kept continually running with a plug arrange- ment to connect either set to aerial. This entailed three separate receiving circuits-
(1) Marconi Auto-call circuit with receivers complete. (2) Radio Auto-call circuit with receivers complete,
(3) The ordinary Marconi ship receiving circuit (used only
for weather reports and Press news).
Watch was kept on the Auto-call Device Circuits.
Ships were called with the special signal QZZ, and after making the special signal were asked to repeat it every hour without further call. Position and course were plotted by the Navigating Officer on the bridge; a check position was asked for when
necessary.
As soon as one set worked, the plug was shifted to the other device, so that in every call both sets at least had one test or generally two, depending on the number of longs required to work each set. During strong atmospherics the sets took more than three longs to operate.
Radio
Range.
Radio
Record.
G.P.O. Marconi. Communi-
cation Co.
Distance.
Record.
Marconi. Communi-
cation Co.
Number of tests
278
263
Number of Tests
233
Under 75
miles.
Number of Failures
49
Percentage of Failures
21%
225 24 10.7%
224
Number correct
224
219
Power
18 8.1%
Number of failures
54
44
Under
75 Miles.
Percentage of failures
19.4
16.7
Number of tests
98
86
Number of Tests
111
103
101
Number correct
87
62
Over 75
Number of Failures
41
29
18
Emergency
Number of failures
11
24
miles.
Percentage of Failures
87%
28.2%
17.8%
Percentage of failures
11.2
27.9
Atall
Number of tests
580
431
Number of Tests
550
505
491
ranges,
Number correct
475
379
Number of Tests Correct
435
399
141
Power
many of
Number of Failures
115
106
47
which are
not re- corded.
Percentage of Failures
20.9%
21·0%
9.6%
Number of False Calls...
39
3
2
Over 75 Miles.
Number of failures
105
52
Percentage of failures
18.1
12.1
Number of tests
52
48
Emergency
Number correct
32
13
Number of failures
20
35
Percentage of failures
38.5
73.0
189
Greatest range of a correct test
189
189
| 2200
Number of tests
41
46
FFU made a dash of over 15 seconds, before transmitting, and G.P.O. set worked.
Not stated.
Power
Number correct
32
Number of failures
9
Percentage of failures
22.0
19-6
சம5
37
9
Total number of tests...
1,049
374
At all ranges.
Power and Emergency
Total correct Total number of failures Percentage of failures Number of false calls
850
710
199
164
23.4
18.8
5
2
Greatest range of a correct test
From shore station (Karachi)... From ship (H.M.S. "Cleopatra,"
Marconi, S.S." Plassey," Radio Communication Co.)
1,029m
840m
314m
202m
65
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