Field Report: Broadcast Tools Site Sentinel 4


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Tucked into a corner of the transmitter room at WILS in Lansing, MI, are two racks full of equipment that constitute the uplink for the Michigan Farm Radio Network. This satellite delivery provider began almost 30 years ago in the corner of a parking lot in Milan, MI, and served affiliates with farm market news that impacted a tri-state area.

When Saga Communications purchased the system and moved it to the present Lansing location, the expansion of services soon included uplinking the Detroit Tigers, Lions, Pistons and Red Wings. This was followed by the Illinois Radio Network with studios in Chicago, and most recently, the Minnesota News Network, with its main studios in Minneapolis/St. Paul.

For many years we have depended on various Broadcast Tools equipment to permit dial-up audio monitoring, remote switching and, most recently, Internet-based control of re-boot functions for two Nexus ISDN codecs using the Broadcast Tools Web Switch. It soon became obvious that we needed more capability than existed with our previous dial-up units.

Affiliate access

Engineer Ralph Haines, Michael J. Ostlund from the Minnesota News Network, Dennis Mellott, Saga’s GM in Lansing, Stephen Paul from the Saga Detroit office, and I all put our heads together to plan for a system that would permit access to all five affiliates’ T-1, ISDN, dial-up and alternate program systems. This is where the Broadcast Tools Site Sentinel 4 entered the picture.

The recent installation of a hi-speed Internet connection into the uplink site to accommodate our Web Switch opened a whole new venue for remote control and monitoring. The Site Sentinel 4 is a cost-effective, 1/3RU device for Web-based remote control, monitoring, status alerts and relay interface with other equipment from virtually anywhere with access to the Internet. This includes the newest Web-capable hand-held devices.

Reviewing the Site Sentinel’s capabilities gave me the immediate impression the designer had been sitting in on our brain-storming sessions all along; here was a tool that included analog metering for four separate channels, status monitoring for four channels, four logic relay interfaces for direct interface with other equipment, a stereo silence sensor, a built-in power loss detector, a separate set of contacts for remote power control via a third-party device and an optional temperature probe. All of these features are programmable in numerous manners to accommodate a host of user requirements.

Every feature of the Site Sentinel 4 can be accessed over any IP network, including a private network, IP-based industrial control network and, of course, the Internet. It even features a logging system for parameter snapshots, alarms, status, metering and temperature sensing that will e-mail anyone of eight recipients with routine metering and/or alarm situations.

The device is equipped with four buffered high-resolution 10V metering (analog) channels, four optically isolated status/logic channels configured for 5 to 24Vdc wet or dry inputs (user selectable with jumpers), four channels of SPST 1-amp relays that may be latched on or off or pulsed with user-defined timing. It also features a separate, isolated relay with user-selectable contact assignment to interface with an external device, such as Middle Atlantic RLM-15-1C, 20-1C or RLM30-L530-1 ac controller devices to turn higher current external equipment on, off or reboot as required. SNMP and SMTP username and passwords are also supported.

Because each channel of control can be password protected, it is possible to assign security clearance for each of the four separate affiliates at the MFRN up-link its own password. This permits everyone to monitor what’s going on at any time, BUT limits control functions to those with specific password authority.

Other features

Of course, the Site Sentinel 4 has the regular features we’ve all come to expect from Broadcast Tools: euroblock screw terminal connections for metering, status/logic, control relays and the stereo silence sensor. There are two separate power supply jacks, one for the power input to the unit, and another for the optional loss-of-power input. The temperature probe input is a 1/8” TRS jack for the optionally supplied probe, programmable for Fahrenheit or Celsius indication. Front panel LEDs indicate relay and status states, local operation (a nice safety feature when connected to external high-power transmitters or other devices), rear-panel RJ-45 10/100base-T LAN/Ethernet interface, a fully RFI-shielded enclosure and a surge-protected power supply. As with all other Broadcast Tools products, the front and rear panels are clearly labeled so connections and functions are almost intuitive. The Site Sentinel 4 fits nicely into the optional rack-mount shelf. As another side note, I like to use the Furman Plug Lock power strip for the wall-wart style power supplies. This device permits five separate wall-wart supplies to be secured into one rack-mountable plug strip.



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