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| 503-642-9693 |
| Sales |
| Technical Support |
| Custom Products |
| Search |
Our IRIG-B clocks displays days, hours, minutes and seconds. Our AOS/LOS clocks have dual timers that are synchronized to an IRIG-B master clock time source. The AOS clock indicates the hours, minutes and seconds until the acquisition of the signal. The LOS clock indicates the minutes and seconds until the loss of the signal.
One of the applications of an AOS/LOS clock is to track satellites or other objects in orbit that are not geo-synchronous with the earth's orbit. When the object appears over the horizon, we say we have Acquisition of signal (AOS). This may take hours or even days until the next appearance of the object.
Once the object appears, communication is possible. The appearance may be just minutes or may be hours. It may be desirable to communicate with the object to correct problems, collect data, perform routine maintenance or upload critical information. The object passes overhead and eventually falls below the horizon. This is termed Loss of signal (LOS).
Alzatex manufactures clocks specifically designed to display AOS, LOS or both. These clocks are available in several standard sizes. The most common sizes are one inch, 4 inch or 5 inch high digits.
The AOS/LOS timers also include a remote keypad for setting the AOS and LOS times.
These units are available with an IRIG-B input for synchronizing with your GPS. Other data formats are available including SMPTE time code, NMEA and others. Contact Alzatex with your requirements.
Why IRIG-B. The need for IRIG standards such as IRIG-B is that standardization of time codes allows equipment to be synchronized to a known reference time. This also allows facilities at geographically separated locations to synchronize to a known time code source. In practice, many labs are equipped with devices that create IRIG time code from GPS Satellite time and distribute time code to other devices for synchronization.
What is IRIG-B? The IRIG-B standard consists of a family of rate scaled serial time codes with formats containing up to three coded expressions or words. The IRIG-B pulse code contains one "frame" of 100 "elements" per second for the time of the year and GPS receiver status. IRIG-B encodes day of year, hour, minute, and second data on a 1 kHz carrier frequency, with an update rate of once per second.
IRIG-B Uses. Modern day electronic systems such as communication systems, data handling systems, missile and spacecraft tracking, and telemetry systems require time-of-day information for data correlation with time. In 1956 the TeleCommunication Working Group (TCWG) of the American Inter Range Instrumentation Group (IRIG) was mandated to standardize the different time code formats. IRIG document 104-60 had defined the original IRIG formats, was revised in 1970 to IRIG Document 104-70, and published later as IRIG Standard 200-70. The latest publication is 200-98.
IRIG-B Time Code. The time codes, originally developed by the Inter-Range Instrumentation Group (IRIG), now used in government, military and commercial fields. There are many formats and several modulation schemes, but they are typically amplitude modulated on an audio sine wave carrier. The most common version is probably IRIG-B, which sends day of year, hour, minute, and second data on a 1 kHz carrier frequency, with an update rate of once per second. More information about the IRIG-B code is available at www.wikipedia.org/wiki/Inter-range_instrumentation_group_time_codes.
The most common sizes are listed below. Other sizes available. Call us for details.
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For a given pass of a satellite relative to a particular observer, there are three important times:
For circular orbits, TCA is usually near the halfway point, and corresponds to the maximum antenna elevation (highest point in the sky). For elliptical orbits, it could occur at AOS or LOS. Refer to www.sat-net.com for some interesting information to Amateur Radio Operators.
