LRU User Manual March 2002
To contact SERCEL Nantes, France Commercial; Customer Support; Manufacturing & Repair. B.P. 439, 16 rue de Bel Air 44474 Carquefou Cedex Tel: +33 2 40 30 11 81, Fax: +33 2 40 30 19 48 Hot-Line: Land: +33 2 40 30 58 88 Marine: +33 2 40 30 59 59 E-mail: sales@sercel.fr customer.support@sercel.fr www.sercel.com St Gaudens, France Vibrator Customer Support; Vibrator Manufacturing & Repair; Streamer Manufacturing & Repair. Tel: +33 5 61 89 90 00, Fax: +33 5 61 89 90 45 Hot Line: +33 5 61 89 90 91 Alfreton, U. K.
LRU User Manual General The LRU (Line Remote Unit) relay is a long range point-to-point radio relay cell that can be inserted anywhere in a spread as an element of the 408UL network to relay the data transmission on a Line or a Transverse. It connects to any type of 408UL field electronics (LAUX, LAUL, FDU Link, etc.). Built in the LRU is a full performance LAUX.
Typical setups Typical setups CAUTION If you wish to test a radio relay cell through a wireline link between the coaxial connectors of two LRUs, use a 60 dB (minimum), 20 W attenuator. Attenuator 20 W 60 dB min. (test setup) 12 V For optimal performance of the radio link, do not place any electric device (including LRU, FDPA408, etc.) on the same side as the radiating elements! LRU 12 V NO 12 V LRU 12 V The antenna should be at the top the mast.
LRU User Manual Typical setups CAUTION Antenna height is limited to 6.1 metre near airports. Below are typical examples of setups along with the associated specifications in terms of covered range and transmission capacity. Basic radio relay cell . 7-element Yagi antenna LAUX and radio functions See 1 below Line or Transverse to Central Unit LRU 12 V LRU Coax downlead 12 V Battery Typical performance (Ground-Wave propagation above flat terrain): 1 - Range: 24 km, 60 Ch @ 2 ms, Real time.
Typical setups Radio relay in series connection To extend the relay range, you can use two relay cells in series connection as shown below. You can choose between two types of series setups, one with fewer antenna masts to raise, the other optimizing the data rate. • Two-mast series setup (high data rate) Requirements: - At least 300 m between antennas, - At least 13 MHz frequency separation.
LRU User Manual Typical setups • Single-mast series setup Line or Transverse to Central Unit LRU See 1 below See 1 below 12 V Battery LRU LRU 12 V 12 V LRU 12 V (Line or Transverse cable) Typical performance of each relay cell (in Ground-Wave propagation conditions above flat terrain): 1 - Range: 24 km, 30 Ch @ 2 ms, Real time. - Range: 10 km, 120 Ch @ 2 ms, Real time.
Typical setups Where more than two relay cells are used in “single-mast series connection”, you can avoid reducing the data rate any further if you still work with only two Subframes, provided adjacent relay locations do not use the same Subframe. In the example below, relay cell (A) can use the same Subframe as relay cell (C) if they are distant enough and if they use two separate frequency channels. (A) LRU 2 LRU 4 (C) LRU 1 (B) LRU 3 Relay Cell (A) (B) (C) 1-6 LRU No.
LRU User Manual Typical setups Radio relay with REM Requirements: - At least 300 m between antennas, - At least 13 MHz frequency separation. Line or Transverse to Central Unit LRU See 1 below SU6R 12 V LRU Battery 12 V REM (Transverse cable) SU6R SU6R Insert a bandpass cavity filter for each REM (case of multi-REM setup) and one more if Audio is used with SU6-R 12 V Typical performance of each relay cell (in Ground-Wave above flat terrain): 1 - Range: 24 km, 60 Ch @ 2 ms, Real time.
Typical setups Requirements: - At least 300 m between antennas, - At least 13 MHz frequency separation.
LRU User Manual Antennas Antennas The LRU is used as a point-to-point radio relay. For a stationary relay, directional antennas are used, allowing maximum performance and protection from interference. Where one of the two LRUs involved in a radio relay is subject to roving (Marine, Shalow-water operation, etc.) omni-directional antennas are more suitable. Directional antenna Below are the specifications of a wide-band, 7-element Yagi antenna available from SERCEL.
Antennas 1-10 • Feed Impedance: 50 ohm. • Connector type Type UHF. • Antenna Boom length: 1.9 m (75"). • Longest Element: 68 cm (26.772"). • Shortest Element: 48 cm (18.898''). • Weight: 900 g (2 lb). • Maximum mast OD: 5 cm (2").
LRU Specifications GENERAL PHYSICAL Radio Functions Communication with another LRU for data transmission with error recovery and temporary storage Cable Functions full LAUX capabilities Tests capabilities Power supply Radio data transmission Cable data transmission Field tests Instrument tests Antenna spectrum monitoring capability Radio setup Pocket terminal connection capability Memory 4Mb local buffer for non-real time transmission mode Interval between LRU's or LRU and LAUX on transverse Up
