The Bird 3141 Channel Power Monitor Display monitors all aspects of your LMR system. Continuously monitor radio performance, combiner loss, and antenna/feedline characteristics to identify and alarm critical changes. With the data logging function, long-term performance monitoring can be used to identify changes before they negatively impact the system enabling your preventative maintenance team to address problems before they occur. Solutions are available for the entire range of land mobile radio frequencies from 144 MHz to 940 MHz.

Setup and monitoring are simple with the built-in web server available anywhere there is an internet connection and a web browser, so it is as close as the computer on your desk or your mobile phone using our Android app. Receive SNMP alerts or just check up on your system at your convenience.

Multiple versions available

Bird offers two versions of its 3141 Channel Power Meter - the 3141A15 and 3141A48. An overview of the main characteristics of each can be seen below.

• 3141A15
• Input voltage: +15VDC (supplied by AC adapter)
• Input current: <3A
• Fuse rating: 5A
• 3141A48
• Input voltage: ±48VDC
• Input current: <1A
• Fuse rating: 1.25A

Compatible power sensors

The 3141 is compatible with a variety of power sensors and can monitor up to 16 non-directional and 16 directional sensors simultaneously.

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• Model 4044
• Non-Directional Power Sensor measures output power of either analog or digitally modulated radios up to 125 watts
• Model 4042
• Directional Channel Power Sensor provides power readings by individual channel
• Model 4043
• Directional Power Sensor provides composite power readings

A CPM is capable of monitoring both analog and digital power sensors, a single CPM may monitor a maximum of 16 analog sensors and a maximum of 16 digital sensors simultaneously.

Analog power sensors

The CPM is capable of monitoring up to 16 individual analog power sensors simultaneously. A typical CPM installation is shown in the image below. In this example, both non-directional and directional Analog sensors are used to monitor system performance.

Non-directional power sensors (model 4044) are placed between each radio and the inputs of the combiner. These sensors measure the power output of the radios and transmission lines. Changes in a radio’s output power level as measured at the CPM can generate alarms. A directional sensor is placed in line with the output of the combiner to measure forward power and reflected power, thus providing a measurement of total output power and the capability of measuring VSWR. With such positioning of directional and non-directional sensors, it is possible to spot degradation or failure at specific points in the system. This power sensor-based measurement approach helps improve the reliability of the LMR system.

Each Analog sensor is connected to an analog sensor input on the back of the CPM, only 16 analog input ports are available on each CPM. A system is limited in the number of analog sensors that can be monitored by the number of ports available on a CPM, to monitor more than 16 analog sensors, additional CPMs must be used. Another option is to add Digital Power Sensors to the system.

Digital power sensors

The CPM is capable of monitoring up to 16 individual digital power sensors simultaneously. A typical CPM installation is shown below. In this example digital sensors are used to monitor system performance.

Digital sensors offered by Bird are directional sensors capable of measuring forward power and reflected power, thus providing a measurement of total output power and the capability of measuring VSWR.

4043 model digital sensors are available in a variety of frequency ranges and must be matched to the bandwidth in use. The 4042 model digital sensors are channel sensors, these sensors are unique in that they are able to measure the forward power, reflected power and VSWR of up to 16 SINGLE Channels in the presence of multiple channels at the output of a frequency combiner.

The digital sensors use an RS-485 serial bus for data transfer to and from a CPM. Each sensor is equipped with two RJ-25 jacks, either jack may be connected to a CPM. The second RJ-25 jack may be used to extend the RS-485 bus to another digital sensor, as seen in the figure below. Multiple sensors may be serially connected in this fashion, allowing as many as 16 sensors to be connected to a CPM.