BJ LINC Technical Support — Glossary of Terms
Access Number (Dial-Up Only)
The phone number to your Internet Service Provider (ISP). Your CCU automatically dials this to connect your classroom to BJ LINC for interactivity when using a dial-up connection.
Azimuth
The angle of horizontal rotation (left and right) of the dish required to point at a specific satellite (0 degrees is north, 90 degrees is east, 180 degrees is south, and 270 degrees is west)
CCU (Classroom Control Unit)
The computer at the BJ LINC school that controls all student interactivity. It connects to the BJ LINC studios through the two dedicated telephone lines or through a local broadband connection and one dedicated phone line.
Dish
Commonly used term for a satellite antenna. This large concave part gathers the satellite waves coming through the air and focuses them into the LNB.
Downlink
Term used to refer to the signal sent from the satellite down to the earth
Downlink Frequency
Term used to refer to the frequency of the signal coming from the satellite to the earth. The downlink frequency for our signal is 11750 MHz.
Elevation
The angle of upward tilt, measured in degrees, required to point the dish at a specific satellite
IRD (Integrated Receiver Decoder)
Electronic device that takes the scrambled signal from the satellite dish and translates it into picture and sound
IRU (Interactive Response Unit)
The telephone-like device that allows the student to interact with the teacher
IRU Login
The process at the beginning of every BJ LINC class whereby the student enters his personal identification number into an IRU to record class attendance and make interaction with the teacher available for the duration of the class
ISP (Internet Service Provider)
A company that provides to you, via a phone or cable connection, access to the Internet, which is used by BJ LINC as a vehicle for connecting your school to our studios
KU Band
The range of satellite frequencies that operates from 10,700 to 18,400 MHz. Our satellite signal operates within this range.
LAN (Local Area Network)
A group of computers at your site that can communicate with each other. In order to use your LAN instead of the second phone line, your network must have a connection to the Internet.
LNB (Low Noise Block downconverter)
Device that mounts on the front of the dish and converts the direct satellite signal, sending it along a cable to your receiver
Local Interference
Term that refers to anything in a customer’s local vicinity that interrupts the satellite signal temporarily or possibly at regular intervals. Common sources are inclement weather, radar detectors, and car alarms.
Look Angle
The angle at which an antenna must be aimed in order to see a particular satellite. This includes Azimuth and Elevation.
Polarization
Term that refers to the offset of the LNB compared to the starting position, which can be adjusted (rotated) to maximize signal quality
Rain Fade
Signal interruption due to heavy rain in your local area or at the uplink
Satellite Dish/Antenna Alignment
The satellite dish must be aligned with the satellite that broadcasts the BJ LINC signal. If the dish is moved even slightly, the signal will be lost until the dish is realigned. The term “peaked” is often used to describe the condition of your dish when it is in its optimal alignment.
Satellite Receiver
(See IRD.)
Signal Quality
A value that represents the level of signal coming from our satellite. A high value (>80) indicates noise-free reception of our signal.
Signal Strength
A value that represents the level of signal gathered by the dish. This value is high (~50) when the dish is pointed to our satellite OR when an interferer is injecting a high-level interfering signal.
Solar Fade
A signal degradation phenomenon that affects the transmission of satellite signals every March and October. This is caused by radiation from the sun when it is directly behind the satellite and in a direct line with the receiving dish.
Uplink
Term used to refer to the signal sent from the earth up to the satellite.
