Vemco

About Us

VEMCO was first registered in November 1979. Founder Fred Voegeli started the company to manufacture ultrasonic fish tracking transmitters. Fred had completed his masters degree in Electrical Engineering at the University of New Brunswick (UNB) and worked with Dr Doug Pincock in the Ultrasonic Telemetry Lab (aka. Fish Lab). In order to manufacture the miniature and complex circuits VEMCO purchased a Lead Bonder, a machine which could interconnect semiconductor chips in their unpackaged state. At that time VEMCO did not have a receiver but marketed the Communications Associates Inc (CAI) CR-40 receiver and CI-40 decoder. The CR-40 receiver was a great narrow band receiver but required a separate crystal for each transmitter frequency. It is worthy of note that the companion CI-40 decoder was designed by Doug Pincock under contract to CAI in 1977.

The VEMCO VR-60 receiver was designed in 1982 and was the first frequency synthesized ultrasonic telemetry receiver, it could also contain an optional decoder and LCD display. This allowed the user to display data from transmitters in Engineering units and save the data to an internal memory circuit board. Algorithms were developed to automatically detect and log the time and date of fish passing by a stationary VR-60 receiver. The transmitter types used were crystal controlled ¿pingers¿ (aka. Fish tags) which transmitted a tone at a very accurate repeat interval. The identification algorithm looked through a list of pre-entered intervals to determine which fish were present. The algorithm could identify up to ten tags present at the same time. By using multiple frequencies up to 100 fish could be identified. Some years later the automated fish tag detection features of the VR60 were packaged in an underwater simplified receiver called the VR20.

The VRAP system which was developed in collaboration with Dr Ron O¿Dor of Dalhousie University Biology Dept in 1985 provided precise positioning of tagged animals in their natural environment. VRAP positioning systems are still in production and have been adapted for military diver training and underwater surveys of historic sites.

In order to expand the number of unique ID¿s available and to reduce the effects of man made periodic noises from seal scare devices and sounders, a new coding scheme was introduced. Instead of a fixed rate pinger transmitting continuously, the new scheme transmitted an infrequent code burst lasting a few seconds. The code is repeated at a pseudo-random rate so that code collisions will not continue between two tags. This approach increased the number of unique ID¿s to 256 on each frequency. Perhaps more importantly it allowed the use of very low power single frequency receivers (VR1) which could be submerged for over 6 months to gather data from passing fish tags.

The other significant development at that time was the miniaturization of transmitters to the level where they could be implanted in wild Atlantic salmon smolts. Furthermore the new miniature tags had to generate the new pseudo-random codes. VEMCO invested in custom silicon to provide all the circuitry on one silicon chip which would run at sub-microamp current levels. The resulting V8SC (SC for Single Chip) tag was a breakthrough in size, complex coding and extended battery life.