Are weak signals and poor coverage a problem? Is there a solution?
The solution is the KVT 8000 Automatic Voting Receiver Selector. The technique is selection among signals from several receivers based on precise and continuous measurement of signal quality.
The result is enhanced communications range for low powered portable and mobile units.
Why Receiver Voting?
Radio systems typically consist of a high power base station or repeater and many low power portable and mobile units. The high power base station can easily cover a large area with a strong high-quality signal but due to their relatively low power, the mobile units simply cannot reach the base station with a high quality signal from everywhere within the desired coverage area.
Communication with mobile units operating in weak signal areas can be unreliable at the very least. In severe cases when there are "dead spots" in the desired coverage area - communication becomes impossible. The consequence for operating with unreliable and "spotty" coverage can be a costly-waste of time that leads to frustration, mistaken information, and complaints.
Fortunately, there are ways to overcome these problems. A very effective way to improve coverage and avoid a weak signal problem is a multiple receiver voting. Multiple receiver voting systems use several receivers so that at least one receiver always receives a high quality signal from portable and mobile units operating anywhere within the desired coverage area.
The key to maximizing performance in multiple receiver systems is an automatic voting receiver selector, such as the KVT 8000 that can monitor all receivers in the system and continuously select the receiver having the best signal quality. As mobile units travel through the desired coverage area the KVT 8000 instantly switches from one receiver to another to insure that the best possible signal is always on-line.
Multiple Site Systems
Multiple receiver systems can be either single-site or multiple-site systems. Multiple site systems use remote receivers located throughout the desired coverage area so that at least one receiver always hears a high quality signal from every portable and mobile unit. The remote receivers are linked to a KVT 8000 automatic voting receiver selector at the central site where the KVT 8000 listens to all receivers and automatically selects the receiver having the best audio quality.
The multiple site system has a main receiver at the central site and two remote receivers located in weak signal areas. Each remote receiver covers only a small portion of the total coverage area. System costs are controlled because premium high-elevation sites and expensive antenna towers are usually not required at the remote sites.
The versatile KVT 8000 also controls costs by inter facing to a wide range of link arrangements-VH F/UHF radio, microwave, and wire-lines. In addition, its built-in test capability allows the performance of all receivers and links to be monitored readily at the central site.
The KVT 8000 votes among three receivers - the central site receiver and two remote receivers In general, the number of receivers used depends on how many weak signal zones there are in the desired coverage area. The KVT 8000 Voter is ideally suited to a wide range of applications from small systems, having as few as two receivers, to super-large systems having as many as 32 receivers.
Single Site Systems
Single site systems are a cost effective way to get the advantages of multiple receiver voting. A single site system uses three receivers with one receiver connected to an omni-directional antenna and the remaining receivers connected to high gain directional antennas. The three receivers are directly connected to the KVT 8000. By using high gain antennas the effective signal received from hand held portables can make them sound like high powered mobiles and mobile units can sound like base stations.
Why the KVT 8000?
In many applications multiple receiver voting is the best way, if not the only way, to improve system coverage. In the past there were two choices available in receiver voting selectors – the high cost voters that delivered high performance because they used a signal-to-noise ratio as an accurate criterion for voting or the low cost voters that provided poor performance because they relied only on a simple signal level measurements. Today there is a better choice, the KVT 8000. It delivers a high performance based on precise signal-to-noise evaluations at modest cost.
The KVT 8000 raises performance to a new level by including a full monitoring and metering for rapid installation and system maintenance. It adds versatility through options that allows the KVT 8000 to adapt easily to a wide variety of applications. The outstanding performance and versatility combined in the KVT 8000 makes this multiple receiver voting the preferred cost-effective way to obtain reliable coverage.
Voting based on signal to noise ratio.
The KVT 8000 uses separate peak and valley detectors on each input channel to calculate signal-to-noise ratio so it always votes the channel having the highest audio quality-it is never fooled like simple voters that rely on RF or audio level.
Fully independent detection circuitry on each channel monitors all receivers continuously without gaps like those that can occur in sampled systems.
Pre-channel gain equalization.
Pre-channel gain adjustments allow every channel to be set to the same identical level to obtain a truly transparent switching between receivers. Separate activity detectors are included on each channel. In the event of a receiver or link equipment failure, the detectors automatically disable the failed channel and give a visual status indication.
Quiet Channel Lockout.
Separate activity detectors are included on each channel. In the event of a receiver or link equipment failure, the detectors automatically disable the failed channel and give a visual status indication.
Built-in alignment and self test features.
Front panel indicators and metering allow monitoring of the audio level on any channel. The metering plus built-in speaker and self- test features enable precise alignment and diagnosis of link or receiver problems.
The KVT 8000 is available in 8-channel or 4-channel versions to economically match the needs of large and small systems. In addition, provisions exist for interconnecting several units together to vote as many as 32 receivers in very large systems.
The standard high impedance audio inputs are ideal for connecting to VHF/UHF radio links microwave links, or directly to receivers low impedance inputs and 1950 Hz idle channel tone detectors are provided on channels equipped with the low impedance wire-line option. Channels may be configured individually for high or low impedance operation for use in systems using both radio and wire-line links.
Logic inversion switches are provided on all control (COS) inputs to match various link and receiver arrangements. In addition, per channel inputs are provided for remote disabling of individual channels. Logic inversion and optional relay switched output control is available.
The KVT 8000 is mounted in a handsome 19-inch rack mount cabinet with front panel metering, speaker, and indicator lamps. Audio jacks and logic terminals are conveniently accessible on the rear panel. Active voter circuitry is contained on a high quality, silk-screened, solder masked, epoxy fiberglass printed circuit board. Access to all active components and adjustments is readily gained by removing the unit top cover. Included within the cabinet is a rugged AC power supply and provisions for DC backup power. Space is provided within the cabinet to contain two MR-4 receivers.
All ACS products are guaranteed in materials and workmanship for 1 year from the date of purchase. Please
contact us for complete details.