Simulcast System Assembly in Progress...
This rack contains most of the equipment that will control the simulcast system. Included is the simulcast controller, network control, data and audio distribution, and network switch.
Spread out here for testing is the audio, data and control equipment for the three simulcast sites.
A closeup picture of the equipment in the Chester rack, which includes the multiplexer, microwave radio, radio control and repeater interface rack, the Tait 2m repeater, and the simulcast controller.
The controller cards which will process the audio to and from the sites are being aligned.
You can see the output of the simulcast controllers here on the scope. Traces 1, 2 and 3 are the outputs from the simulcast controllers that will be placed at the sites, AFTER the audio is sent through all of the networking equipment. Trace 4 is the source as it's fed into the central controller. For the system to work properly, the phase of the audio as well as the transmitter oscillators must be sync. This system uses GPS-based timing to lock the transmitters and audio to an accurate timebase. Transmitter control and transmitted audio are passed through a TCP/IP network from the central controllers to the sites.
A picture of the 441.500 repeater on Mt. Hope. This one is a little prettier than the 2m, but still only temporary.
The empty Mt Hope Racks ready and waiting for equipment.
The intermediate microwave relay point between Mt Hope and Hosac Mtn. That's KB1NZN's 2m/440 dual band antenna on top. :-)
The channel card being developed here will provide the interface between the repeater RF and the backbone of the system. This is a brand new channel card design, which will see it's first action (outside of the lab) on the Amateur system. The only function the repeater provides is RF. All of the CTCSS, tone decoding, generation, signalling and in the commercial side of the system trunking encoding and decoding is handled on this board. The board also processes the audio to and from the RF and converts it to and from a PCM stream.
For the simulcast system we are using these Tait repeater modules. They were formerly used by the US Forest Service.
This is one of the Tait repeater modules getting tuned up for 2 meters. All of the tone generation and decoding boards have been removed since those functions are provided by the channel card.
We are lucky enough to have a nice HP network analyzer to work with. At all of our radio sites we are generally limited to one antenna per band for both RX and TX on the towers to combine 2 meter, 440, GMRS repeaters, three channels of VHF trunking and three channels of UHF trunking into. At two sites we do have an additional antenna at each, but that is mostly because of the band spread requirements in the commercial licenses. Accomplishing this combining feat would be impossible without this tool.
Some of the combiner cans being tuned on the network analyzer.
This is Cleocat's CFO (Chief Feline Officer), Curly Tail. She often ensures that the power supply in this rack is working correctly.
Curly Tail sometimes is quite active in company management, often inspecting the schematics as they come out of the printer. She is very particular and rarely allows mistakes.
We have to be careful though. She sometimes monitors our activities without us knowing. You might think she's napping here, but in reality she is listening to VoIP packets.... ;-)