Tuesday, February 10, 2009

Cross-Band Internet Bridge

An INTERNET Bridge Computer establishes a Skype conference with Base Station 1 (BS-1), Base Station 2 (BS-2), and up to 25 Internet Participants (IP) parties. BS-1 is in contact with any number of HF participants on 7.230. BS-2 is in contact with any number of HF participants on 3.968. The transceivers (XCVRs) at BS-1 and BS-2 are set for VOX operation with their thresholds to only open on a solid Q5 signal. All participants must follow good round-table protocol, clearly identifying who is to get the mic on the next over.

Situation (1)
An HF participant is talking on 7.230. BS-1 receives the signal and sends it out over the Internet conference. All Internet Participants (IP parties) and BS-2 will hear the signal via the Internet conference. With BS-2’s open VOX, the HFP’s signal will be retransmitted on 3.968.

Situation (2)

An Internet participant is talking. The signal goes out over the conference link. BS-1 and BS-2 retransmit the signal on 7.230 and 3.968 respectively.


Internet participants can talk to each other full duplex. These full duplex conversation will be retransmitted by BS-1 and BS-2.

Situation (3)

HFP-1 on 7.230 is talking. His signal is retransmitted by BS-2. There is nothing to prevent Internet participant IP-1 from talking—other than good round table protocol.


If an HFP on 7.230 and an HFP on 3.968 start to talk at the same time, who ever opens the corresponding VOX first wins and a classic double occurs. For example, suppose HFP-1 on 7.230 starts talking a fraction of a second before an HFP-3 on 3.968. HFP-1 will key the VOX on BS-2, blocking reception of (or double with) HFP-3. Should HFP-3 start talking a moment before HFP-1, HFP-3 will capture the VOX on BS-1 and block reception of (double with) HFP-1.


When 40m is long, round tables are limited to distant stations. For example, typically on 40m N0SAP, KB4BW, can hear each other; W4UOA, WA5MLF, and W4BXI can also hear N0SAP and KB4BW. However, W4UOA, WA5MLF, and W4BXI can not hear each other. With the Cross-Band Bridge in place, all communications are retransmitted for full geographic coverage.

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