{{Short description|Type of radio frequency converter}} thumb|upright=1.6|Tampa Microwave Lab LTT-03-1RU-107 Test Loop Translator with adjustable output frequency and attenuation A '''test loop translator''' ('''TLT''') is a type of radio frequency converter or heterodyne, used to translate between uplink and downlink segments (generally in the same band), to allow for "loop-back" testing and calibration of a satellite ground station without the need to interface with the satellite.<ref name=novella>{{cite web|title=Test Loop Translator Technical Notes |url=http://novella.co.uk/TestLoopTranslator_details.htm |url-status=live |archive-url=https://web.archive.org/web/20240814223720/http://novella.co.uk/TestLoopTranslator_details.htm |archive-date=14 August 2024 |accessdate=22 July 2025 |publisher=Novella Satcoms Ltd. }}</ref><ref name=atlantic>{{cite web|title=Model ASC 710C Test Loop Translator|url=http://atlanticsat.com/ASC710C.htm|publisher=Atlantic Satellite Corporation|accessdate=23 February 2015|archive-date=19 February 2010|archive-url=https://web.archive.org/web/20100219062003/http://www.atlanticsat.com/ASC710C.htm|url-status=dead}}</ref> The test loop translator is an extremely valuable tool for evaluating the performance of satellite earth stations. It allows the user to carry out analysis, alignment and system testing without incurring satellite airtime costs and the risk of interfering with other satellite users. Thus, it has applications during equipment development, qualification, troubleshooting and in-service routine monitoring.<ref name="Loop Test Translators for Satcom Systems">{{cite web|title=Loop Test Translators for Satcom Systems|url=http://www.atlantecrf.com/pdf_downloads/MJ%20Article%20-%20Loop%20Test%20Translators.pdf|website=www.atlantecrf.com|publisher=AtlanTecRF|access-date=2015-07-31|archive-date=2016-03-05|archive-url=https://web.archive.org/web/20160305165745/http://www.atlantecrf.com/pdf_downloads/MJ%20Article%20-%20Loop%20Test%20Translators.pdf|url-status=dead}}</ref> TLTs generally contain a fixed or preset local oscillator (LO) and a preset gain, though the LO and gain may be adjustable in some models.<ref name=novella/> Most models have a negative gain (i.e., signal attenuation), with -15 dB being the most common value.<ref name=novella/> Test loop translators can cover one or more of the satellite communication bands S, C, X, K<sub>u</sub>, DBS, and K<sub>a</sub>.<ref name="S C X Ku DBS bands">{{cite web|title=Loop Test Translators|url=http://www.atlantecrf.com/products/satellite_communications_equipment/loop_test_translators/s_c_x_ku_dbs_bands.htm|website=www.atlantecrf.com|publisher=AtlanTecRF}}</ref><ref name="Ka Bands">{{cite web|title=Ka Band - Loop Test Translators|url=http://www.atlantecrf.com/products/satellite_communications_equipment/loop_test_translators/ka_bands.htm|website=www.atlantecrf.com|publisher=AtlanTecRF}}</ref>
==References== {{reflist}}
Category:Frequency mixers Category:Electronic test equipment Category:Ground stations
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