User manual GAI-TRONICS L3149B

[. . . ] 43004-023C GAI-TRONICS® CORPORATION A HUBBELL COMPANY Model L3149B C200 Advanced Desk Set GAI-Tronics Corporation 400 E. Mohnton, PA 19540 USA 610-777-1374 800-492-1212 Fax: 610-796-5954 VISIT WWW. GAI-TRONICS. COM FOR PRODUCT LITERATURE AND MANUALS CONFIDENTIALITY NOTICE This manual is provided solely as an operational, installation, and maintenance guide and contains sensitive business and technical information that is confidential and proprietary to GAI-Tronics. GAI-Tronics retains all intellectual property and other rights in or to the information contained herein, and such information may only be used in connection with the operation of your GAI-Tronics product or system. This manual may not be disclosed in any form, in whole or in part, directly or indirectly, to any third party. [. . . ] After the receive audio has been properly compressed, it is passed to A/D section of U15 where it is converted to digital for use by the DSP and also to P400-12 for data conditioning. The input impedance is controlled by U10. When U10-1 is asserted, the input impedance is 560 ohms. When U10-1 is unasserted, the input impedance is bridging. Speaker Audio Speaker audio is originated from the DSP in digital format. The DSP combines the receive audio that is notched for tone control operation, side-tone and beep tones to generate the speaker audio. The speaker audio is converted to analog using the D/A section of U17, and is passed through the volume control stage consisting of U13 and U22 before being passed to the handset earpiece and the speaker amplifier, U18. The microcontroller or the DSP can mute the speaker amplifier. The microcontroller mutes the speaker audio using U5-C8, in cases such as parallel mute or the user muting via a key press. The DSP uses a speaker squelch algorithm to squelch the speaker when no audio is being output to the speaker. This squelch will remain open for two seconds after no audio is present. The DSP then mutes the speaker using U1-88. Transmit Audio Transmit audio is originated from the DSP in digital format. The DSP combines control tones, paging tones and voice audio to generate the transmit audio. It is converted to analog by the D/A section of U15. Upon conversion to analog, the audio is passed through the line-out gain stage consisting of U11 and U10 for level adjustment. U10 also provides the proper line drive and line enable for the transmit audio. The proper level audio is then routed to the line 1 transformer for output from the desk set. 41 Theory of Operation Model L3149B C200 Advanced Desk Set In addition to the transmit audio, data is combined with the transmit audio prior to line-out compensation at U11-3. U10-1 is the line-driver enable for the transmit audio. This provides for a 560 ohm transmit output impedance. Microphone Audio There are three sources for mic audio. These are the internal, handset and audio accessory mic. The microcontroller controls which mic is used based on the source of the PTT. The selected mic audio is gated between the handset/internal and the audio accessory mic by U14 using the outputs of U5-C6. The selection of the handset and internal mic is controlled by U5-C5. [. . . ] Ensure that the line out level is properly adjusted for the L3149B. Ensure that the remote adapter is configured and connected to the radio properly. Ensure that there is a valid circuit line from the desk set to the remote adapter. Ensure that the private circuit is balanced by making sure neither side of the telephone line is grounded. [. . . ]