https://www.ipernity.com/tag/grahamh/keyword/12603 https://cdn.ipernity.com/p/101/7D/6D/290173.buddy.jpg https://www.ipernity.com/tag/grahamh/keyword/12603 Tue, 25 Aug 2026 13:44:27 +0000 Tue, 25 Aug 2026 13:44:27 +0000 https://www.ipernity.com https://www.ipernity.com/doc/grahamh/45892928 tag:ipernity.com,2017-11-26,doc-45892928 Sun, 26 Nov 2017 08:38:34 +0000 2017-11-26T19:38:34+11:00 nobody@ipernity.com (GrahamH) <p class="who"><a href="https://www.ipernity.com/home/grahamh">GrahamH</a> has posted:</p><p class="preview"><a href="https://www.ipernity.com/doc/grahamh/45892928"><img src="https://cdn.ipernity.com/200/29/28/45892928.2df4d647.240.jpg?r2" width="171" height="240" alt=""/></a></p><div class="description">A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: <a href="https://www.ipernity.com/doc/grahamh/24117033" target="_blank" rel="nofollow">www.ipernity.com/doc/grahamh/24117033</a><br /> <br /> E&M signalling over copper pairs in Australia was done using the 4W (1 pair each direction for the audio signal) circuit, ie no additional conductors. This is done in a similar manner to that used in feeding DC power to a condenser/electret microphone in a public address or studio sound system. The direct current for the signalling flows one way equally on both wires of a pair with the earth being used as the return conductor.</div> CommsLinkTestSheet2 <p class="who"><a href="https://www.ipernity.com/home/grahamh">GrahamH</a> has posted:</p><p class="preview"><a href="https://www.ipernity.com/doc/grahamh/45892928"><img src="https://cdn.ipernity.com/200/29/28/45892928.2df4d647.240.jpg?r2" width="171" height="240" alt=""/></a></p><div class="description">A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: <a href="https://www.ipernity.com/doc/grahamh/24117033" target="_blank" rel="nofollow">www.ipernity.com/doc/grahamh/24117033</a><br /> <br /> E&M signalling over copper pairs in Australia was done using the 4W (1 pair each direction for the audio signal) circuit, ie no additional conductors. This is done in a similar manner to that used in feeding DC power to a condenser/electret microphone in a public address or studio sound system. The direct current for the signalling flows one way equally on both wires of a pair with the earth being used as the return conductor.</div> GrahamH https://www.ipernity.com/doc/grahamh/45892926 tag:ipernity.com,2017-11-26,doc-45892926 Sun, 26 Nov 2017 08:38:28 +0000 2017-11-26T19:38:28+11:00 nobody@ipernity.com (GrahamH) <p class="who"><a href="https://www.ipernity.com/home/grahamh">GrahamH</a> has posted:</p><p class="preview"><a href="https://www.ipernity.com/doc/grahamh/45892926"><img src="https://cdn.ipernity.com/200/29/26/45892926.a513461b.240.jpg?r2" width="170" height="240" alt=""/></a></p><div class="description">A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: <a href="https://www.ipernity.com/doc/grahamh/24117033" target="_blank" rel="nofollow">www.ipernity.com/doc/grahamh/24117033</a></div> CommsLinkTestSheet1 <p class="who"><a href="https://www.ipernity.com/home/grahamh">GrahamH</a> has posted:</p><p class="preview"><a href="https://www.ipernity.com/doc/grahamh/45892926"><img src="https://cdn.ipernity.com/200/29/26/45892926.a513461b.240.jpg?r2" width="170" height="240" alt=""/></a></p><div class="description">A two page test report for the transmission links for a two-way radio system. The links joined the track-side base stations and the control centre. The system is no longer in use. This is used for checking the links shown here: <a href="https://www.ipernity.com/doc/grahamh/24117033" target="_blank" rel="nofollow">www.ipernity.com/doc/grahamh/24117033</a></div> GrahamH