© The Institution of Electrical Engineers
Quasi-synchronous operation of a number of base transmitters is often used to provide extensive area coverage in land mobile radio systems. An analysis is made of the responses of an AM receiver operating in such a system. The effects of automatic level control and the muting action are shown to nullify any predictions made of system performance based on harmonic distortion of sinusoidal modulating tones. A limited analysis of the types of distortion likely to arise from the mismatch of modulation between transmitters is made in order to give a guide to the parameters to be explored in subjective trials. The results of, first laboratory-based and subsequently field-based, trials are presented and from them recommendations are made for the allowable limits which should be used for the design and maintenance of a quasi-synchronous AM system.
References
-
-
1)
-
Fudge, R.E.: `A Commutating aerial diversity system', IEE conference publication 162, April 1978, p. 207–209.
-
2)
-
M.O. Al-Nuaimi
.
Response of an AM receiver to a quasisynchronous multi-am-transmitter field.
Proc. IEE
,
3 ,
190 -
194
-
3)
-
(1978)
, CCIR Recommendation 562.
-
4)
-
J.R. Brinkley
.
A multicarrier VHF police radio scheme.
J. Br. IRE
,
128 -
147
-
5)
-
A. Wood
.
(1962)
, The physics of music.
-
6)
-
Asque, V.: `Subjective assessment of tolerances for quasisynchronous amplitude modulation', IEE conference publication 209, April 1982, p. 98–102.
-
7)
-
‘Quasi-synchronous amplitude modulation parameter limits’. Technical Memorandum TM60, Home Office Directorate of Telecommunications, London, England.
http://iet.metastore.ingenta.com/content/journals/10.1049/ip-f-1.1984.0026
Related content
content/journals/10.1049/ip-f-1.1984.0026
pub_keyword,iet_inspecKeyword,pub_concept
6
6