Satellite-communications ( satcom) systems send signals where terrestrial-based wired and wireless systems often fail to go. But monitoring the health and performance of a satcom network requires specialized spectrum-analysis tools with enough accuracy and stability to characterize the quality of satcom carriers. The VC1800 Carrier Monitoring System from Morrow Technologies (St. Petersburg, FL) is such a tool, with a frequency-measurement range of 3 to 1800 MHz and as much as 40 MHz instantaneous bandwidth.

The VC1800 Carrier Monitoring System (see figure) has a standard input range of 3 MHz to 1.8 GHz, with an option (VC-LBD) to cover 100 kHz to 1.8 GHz. The frequency range covers the L-band output range of satcom lownoise block downconverters (LNBs) as well as intermediate frequencies (IFs). The standard reference source is a temperature-compensated crystal oscillator with temperature stability of 1.5± × 10⁻⁷ from +20 to +30°C and aging rate of ±1 10⁻⁶/year. As an option, the VC1800 can be supplied with an ovencontrolled crystal oscillator (OCXO) with improved temperature stability of ±1.4 × 10⁻⁹ from +20 to +30°C and aging rate of ±1 × 10⁻⁷/year.

The VC1800 is a spectrum analyzer with digital resolution-bandwidth filters that are continuously variable from 3 Hz to 1 MHz. It also features an instantaneous bandwidth of 36 MHz with a 70-MHz IF, and option for instantaneous bandwidth of 40 MHz. Frequency spans can be set from 2 Hz to 1.8 GHz, with resolution of 1 Hz. Typical noise sidebands are −130 dBc/Hz for offsets of 10 kHz and greater from carriers at 40 MHz and less, and −90 dBc/Hz for offsets of 10 kHz and greater from carriers spanning 40 to 1800 MHz. The displayed average noise level (DANL) is typically −143 dB from 3 to 40 MHz, −134 dBm from 40 to 500 MHz, −133 dBm from 500 to 1000 MHz, and −131 dBm to 1800 MHz.

The VC1800 occupies only one space (1U) in an equipment rack and offers a variety of bus connections, with 10/100 Ethernet, RS-232 serial, and Universal Serial Bus (USB) interfaces. Optionally, the carrier monitor can be equipped with a standard modem, wireless modem, and Firewire (IEEE 1394) interfaces. The standard communications protocol is TCP/IP, with SNMP available as an option. Simply connect a display screen or computer to the VC1800 by means of one of the above interfaces to monitor signal frequency, signal power, bandwidth, carrier-to-noise ratio and other signal quality parameters from anywhere in the world with access to that interface. The carrier monitor shows signals over an amplitude range of −150 to +20 dBm with overall amplitude accuracy of ±1.5 dB (±0.5 dB at the reference level). Signals can be shown on a screen with a display range of 0.01 to 20 dB/division. The instrument can be run remotely and can be set to automatically monitor carriers and generate an alarm, or perform data logging over time in order to analyze intermittent signal problems.

In addition to the options mentioned, the VC1800 can be supplied with an integrated four-input coaxial switch (option VC-SW4) or an integrated eight-input coaxial switch (option VC-SW8) for remotely selecting multiple input signals. In addition to the standard 19-in. rackmount unit, it can be supplied in a compact form factor measuring just 10 × 11.75 × 3.75 in. Morrow Technologies, 12000 28th St. North, St. Petersburg, FL 33716; (727) 531-4000, FAX: (727) 531-3531, e-mail: vc1800@morrowcorp.com, Internet: www.morrowcorp.com.