20-28 VoIPRemote Termination PanelVersion 1.80PrintingsVersion 1.00:Version 1.01:Version 1.10:Version 1.11:Version 1.60:Version 1.70:Version 8/03/200611/09/2009

TABLE OF CONTENTSSPECIFICATIONS . 11.0 GENERAL DESCRIPTION . 21.1 Description . 21.2 Capabilities and Features . 22.0 INSTALLATION AND SETUP . 32.1 Inspection . 32.2 Disassembly and Reassembly . 32.3 Installation Procedure . 32.4 Radio Connection . 42.5 Ethernet Connections . 52.6 Desk Microphone Connection . 52.7 Speaker Connection . 52.8 Jumper and Test Point Settings . 63.0 OPERATION . 73.1 General . 73.2 Outputs . 73.3 Local Control Option . 74.0 PROGRAMMING PROCEDURES . 84.1 Programming Parameters . 84.2 Audio Adjustments . 154.3 Backup/Restore . 164.4 Information/Status . 175.0 CIRCUIT DESCRIPTION . 185.1 Power Supply . 185.2 Transmit Audio . 185.3 Receive Audio . 185.4 Outputs . 185.5 Local Control . 195.6 Microprocessor . 195.7 Digital Signal Processor . 195.8 Ethernet Interface . 195.9 20-28 VoIP Interface Board . 19APPENDIX A - RADIO INTERFACES . 20Conventional Binary Interface . 20Trunking Radio Interface . 21Additional Radio Interfaces . 21PARTS LISTS . 22SCHEMATICS . 27INSTALLATION DIAGRAMS . 28

SPECIFICATIONSInput Voltage15 Vdc 24W Wall Transformer2.1mm * 5.5 mm barrel conn. Center Current consumption @ 15 Vdc450 mA (TX)800 mA (RX)400 mA (Standby)Temperature range0 to 60 deg CRelative humidity90% at 50 deg CReceive hum & noise-47 dB (ref. 0 dBm)Transmit hum & noise-60 dB (ref. 0dBm) (When using high bitrate codec)Speaker audio output1 W into 4 ohmsDistortion (at rated output) 3% (When using high bit rate codec)Frequency response 1, -3 dB (300 to 3000 Hz)Weight1.5 lb.Dimensions7.5" x 5.5" x 1.5"1

1.0 GENERAL DESCRIPTION1.1 DescriptionThe Model 20-28 VoIP Remote Termination Panel is designed to control remotelylocated base stations or repeaters. The 20-28 VoIP Remote Termination Panel alsosends update information back to the remotes and provides a two-way audio path. Thecommunication between the 20-28 VoIP Termination Panel and the 24-66 VoIP RemoteControllers is done via a TCP/IP Ethernet connection. The operating characteristics ofthe 20-28 VoIP panel are modified using a computer through a web browser accessingthe appropriate IP address that is assigned to the 20-28 VoIP panel. The 20-28 VoIPpanel acts as the master host for all 24-66 VoIP Remotes (up to 20 total) that areconnected to it through the LAN / WAN network. As the 24-66 VoIP remotes areconnected, the 20-28 VoIP panel sets them up with the appropriate personality profile.TCP is one of the main protocols in TCP/IP networks, whereas the IP protocol deals onlywith packets, TCP enables two hosts to establish a connection and exchange streams ofdata. TCP guarantees delivery of data and also guarantees that packets will be deliveredin the same order in which they were sent.The audio between the panel and the remote(s) can be set up for Multicast and/orUnicast protocols. This option is selected in the System Audio Settings screen of the20-28 VoIP and in the Profile Configuration screen of the 24-66 VoIP. From a bandwidthstandpoint, the Multicast protocol is a much more efficient method of transmitting audioto multiple recipients. All audio is sent and received as UDP data packets. See theinstallation diagram and description in the back of this manual for more information onconfiguring for Multicast and Unicast protocols.For applications that require local operation of the base station, a local control option isavailable which includes a speaker jack, volume control, and a desk microphone.(Option RTM-604)1.2 Capabilities and Features PC programmable using WEB Browser G.711, G.723.1, G.726 CODEC algorithms. Non-volatile memory 8 programmable open collector outputs 2 programmable open collector/relay outputs Local control option Remote update Interfaces to various different radios2

2.0 INSTALLATION AND SETUP2.1 InspectionPlease refer to the checklist packed with the 20-28 VoIP in order to become familiar withthe unit and to insure that everything ordered has been received. In the event a part ismissing from the checklist, please call the Customer Services Department at 1-701-2801122.This unit was thoroughly inspected before leaving the factory. If the outer packageappears damaged, please inspect the unit for possible damage immediately. Any dents,scratches, or marks suggest rough handling in shipping. Please notify the shipper if youfind any indications of mishandling. If there are any concerns about the condition of the20-28 VoIP when it is received, please don't hesitate to call the Customer ServicesDepartment.2.2 Disassembly and ReassemblyWhen performing the alignment procedure or making changes to the jumpers on the 2028 VoIP, it may be necessary to remove the printed circuit board from the case. This isaccomplished by removing the two black screws from the front of the 20-28 VoIP andremoving the front panel. Remove the top cover by sliding it off the 20-28 VoIP. Sincethe printed circuit board contains sensitive circuitry, be sure to take the necessaryprecautions against static discharge.To reassemble the 20-28 VoIP, replace the top cover and the front panel, making surethe front and back panels are seated properly with the case. Replace the two blackscrews but do not over-tighten them.2.3 Installation ProcedureThis section provides a basic step-by-step installation procedure for the 20-28 VoIP.Refer to sections 2.4 - 2.8 for detailed installation information. Refer also to the 20-28VoIP installation diagram in the back of this manual. Detailed information on adjustingthe 20-28 VoIP audio levels can be found in section 4.0 Adjustment Procedures.1. The system should initially be set up and tested on the bench. Use only one remoteat first. Additional remotes can be added later.2. Connect the 20-28 VoIP to the base station radio. Be sure to program the basestation radio as required.3. Set the 20-28 VoIP jumpers as required.4. Program the 20-28 VoIP and the remote to allow the remote to control the basestation radio as desired. See the programming procedure for the 24-66 VoIP and forthe 20-28 VoIP.3

2.3 Installation Procedure (cont.)5. Connect the optional wall transformer power supply to power connector on the backof the 20-28 VoIP. If power is being supplied to the 20-28 VoIP from the radio, makesure the radio’s switched B output can supply the necessary current. Also, JP6must be in the correct position. Position AB is for power from radio and position BCis for power from the optional wall transformer.6. Connect the TCP/IP Ethernet connection to appropriate connector on the back of the20-28 VoIP. If the connection being used is also to be shared with an existingcomputer, the computer can be connected to the computer Ethernet connector onthe back of the 20-28 VoIP. This allows the 20-28 VoIP and the computer to shareone network cable. The green link LED on the Ethernet connector should turn onshowing a connection to the network. Refer also to the 20-28 VoIP installationdiagram in the back of this manual.7. Connect a 24-66 VoIP remote to the network. The 20-28 VoIP panel will configurethe remote with the appropriate profile.8. Receive audio from the base station radio should now be heard at the remote.9. Press PTT on the remote. The remote should key the base station radio reliably.10. The remote should also be able to control radio functions such as change channelsor systems and groups on the base station radio if the system is configured for that.11. If the local control option is installed in the 20-28 VoIP, connect the desk microphoneto the 20-28 VoIP and press the PTT button to verify that the radio transmits.12. If the local control option is installed in the 20-28 VoIP, connect a 4 ohm speaker tothe 20-28 VoIP. Remote audio should be heard in the speaker when PTT on theremote is pressed. Adjust the volume control on the front of the 20-28 VoIP asdesired.13. Program any additional remotes as required. Generally, they should be programmedthe same as the first remote. See the programming procedure for the 24-66 VoIPand for the 20-28 VoIP.14. Connect additional remotes to the network15. Adjust the transmit and receive levels of the remotes as required. Audio from allremotes should be set to the same level. Refer to Section 4.2 for AudioAdjustments.2.4 Radio ConnectionThe DB-25 connector labeled "RADIO" on the back of the 20-28 VoIP is used tointerface the 20-28 VoIP to a base station radio. For the pin functions on the DB-25connector, refer to the 20-28 VoIP installation diagram in the back of this manual. Inaddition, Appendix A contains interface information for connecting the 20-28 VoIP toradios.4

2.5 Ethernet ConnectionsThe 20-28 VoIP allows Remote Control of a base station via an Ethernet LAN. Acomputer can also be connected to a remote that is on the same LAN to allow thecomputer access to the network without the need for a hub.The Ethernet connectors are found on the back of the 20-28 VoIP. The Ethernet cableshould be a standard cable that is available anywhere that telephone and computeraccessories are sold. Refer also to the 20-28 VoIP installation diagram in the back ofthis manual.2.6 Desk Microphone ConnectionIf the local control option is installed in the 20-28 VoIP, the desk microphone should beconnected to the modular jack labeled "LOCAL MIC" on the front of the 20-28 VoIP. Theconnections that the local microphone jack provides are detailed in Figure 1.Figure 12.7 Speaker ConnectionIf the local control option is installed in the 20-28 VoIP, a speaker can be connected tothe 20-28 VoIP to allow audio to be heard. A 4 ohm speaker (supplied by the user)should be connected to the speaker plug supplied with the 20-28 VoIP. The speakerplug should then be inserted into the jack labeled "SPEAKER JACK" on the back of the20-28 VoIP.5

2.8 Jumper and Test Point SettingsThe 20-28 VoIP has a test point, number of jumpers, and switches located on theINTERFACE BOARD that controls the operation of the 20-28 VoIP. The jumpers andtheir settings are described below.SW1Position A is for logic level serial interface.Position B is for RS485 level serial interface.JP 5IN for LOW TX Audio impedance.OUT for HIGH TX Audio impedance.JP 6 * AB for POWER from radioBC for Power from External Wall TransformerJP 7AB for open collector output 9.BC for relay output on output 9.JP 8AB for open collector output 10.BC for relay output on output 10.* If using POWER from the radio and not the EXTERNAL WALL TRANSFORMER,make sure the radio can provide the current needed by the 20-28 VoIP. Thedefault is BC for POWER from the WALL TRANSFORMER.TP 4(Test Point 4) allows the panel's network address (including subnet andgateway) to be reset to factory defaults.To begin, disconnect (or verify disconnection of) power. With powerremoved, connect a jumper wire between (ground) the housing of theRJ45 jack (J1 or J6) and TP4. Once this connection is made, applypower. With power applied, the LED on the main board D6 should turnon, turn off, and then turn on again. At this point, the network addresshas been reset and the panel is rebooting, so remove the jumper wirebetween the RJ45 jack and TP4. The panel should finish rebooting.The network address of the panel is now:IP Addresss: Mask:

3.0 OPERATION3.1 GeneralOnce the installation is complete, the 20-28 VoIP panel will communicate with the 24-66VoIP remotes via Ethernet TCP/IP protocol. The remotes will be able to control thefunctions of the radio such as transmit and channel selection, as well as receive andtransmit audio.3.2 OutputsThe 20-28 VoIP contains 10 open collector outputs. Two of these outputs, outputs 9 and10, can also be switched to relay outputs. The outputs are available as general purposeoutputs and can be programmed as active high or active low and also as timed outputs.The outputs are controlled by the remote, which can enable or disable any number ofoutputs with a single update sequence.3.3 Local Control OptionThe local control option allows local control of the base station radio. This optionprovides a speaker jack, volume control, a desk microphone, and other associatedcircuitry. When PTT is pressed on the desk microphone, the 20-28 VoIP will key thebase station radio. Audio from the desk microphone will be passed to the base stationradio for transmission and will also be sent to the network so that the remote users canhear the transmission. If the intercom switch on the front panel of the 20-28 VoIP isdepressed, the 20-28 VoIP will not key the base station radio when PTT is pressed onthe desk microphone. Instead, the audio from the desk microphone will only be sent tothe network to allow the local user to intercom to the remotes.A 4 ohm speaker can be connected to the speaker jack to allow the local user to hearaudio from a remote that is transmitting. Audio from a remote in intercom mode will alsobe heard through the speaker. Receive audio from the base station radio can also bepassed to the speaker. This allows the local user to hear transmissions from other radiosthrough the local speaker instead of through the speaker of the base station radio. Thevolume control on the front of the 20-28 VoIP allows the local user to adjust the speakervolume to a comfortable listening level.7

4.0 PROGRAMMING PROCEDURESAll audio and configuration adjustments are done using a web browser directed at the IPAddress that is assigned to the 20-28 VoIP.The following will explain the adjustment procedure for the 24-66 VoIP. Most audiolevels are factory preset and will, in most cases, not need adjustment. All of the audioadjustment are accessible from a computer using a web browser. The default address is10.0.0.200 with the subnet of The IP address and the subnet addresswill need to be changed to connect to your network. The user name is “admin” and thedefault password is ”idacorp”. Once you logon you should change the password tosomething else to protect your system. If you are configuring multiple 20-28 VoIP Panelsor 24-66 VoIP Remotes, you may need to reset the computer NIC card or restart thecomputer if the next 24-66 VoIP your computer is connected to does not respond. Thefollowing will explain the adjustment procedure for the 24-66 VoIP.4.1 Programming ParametersAll of the programming and audio parameters are accessible through a WEB browser ona PC that is on the network accessing the IP Address that is assigned to the 20-28 VoIP.The default IP Address is The default account name is admin. The defaultpassword is idacorp. It is suggested that the password be changed to protect thesystem. Refer to the Help screens under each of the configuration parameter headersfor more information on programming options.NetworkThe screen below shows the Network Configuration Parameters.8

4.1 Programming Parameters (cont.)RadioThe screen below shows the Setup Radio tab.RadioThe screen below shows the Binary Channel Setup tab.9

4.1 Programming Parameters (cont.)RadioThe screen below shows the Radio I/O tab.OutputThe screen below shows the Output Parameters.4.1 Programming Parameters (cont.)10

ActionThe screen below shows the Action Parameters.ChannelThe screen below shows the Channel Parameters.11

4.1 Programming Parameters (cont.)Remote ConfigurationThe screen below shows the Remote Configuration.RemoteThe screen below shows the Remote Button Parameters for Profile 1.12

4.1 Programming Parameters (cont.)RemoteThe screen below shows the Miscellaneous Configuration for profile 1.RemoteThe screen below shows the Remote Tone Configuration for profile 1.13

4.1 Programming Parameters (cont.)RemoteThe screen below shows the Mini Console Configuration for profile 1.14

4.2 Audio AdjustmentsAudioThe screen below shows the System Audio Configuration tab.AudioThe screen below shows the Local Audio Configuration tab.15

4.3 Backup/RestoreThe screen below shows the Backup / Restore feature.16

4.4 Information/StatusThe screen below shows the Local Information tab.InformationThe screen below shows the Remote Information tab.17

5.0 CIRCUIT DESCRIPTIONThe 20-28 VoIP consists of two circuit boards. One circuit board is the 20-28 VoIPEthernet/Audio platform. The other circuit board is the 20-28 VoIP Interface board usedto make all of the radio and power connections.5.1 Power SupplyPower is supplied to the 20-28 VoIP via the optional 15VDC wall transformer or theswitched B output from the radio. The polarity of the connector must be correct. It isconnected at J18 on the 20-28 VoIP Interface board. It is sent to J10 on the 20-28 VoIPInterface board, then to J10 on the 20-28 VoIP board. From J10 the power is routedthrough a diode D7 and a 1 amp fuse F1. Diode D7 prevents a reverse polarity fromharming the 20-28 VoIP. Power is fed into voltage regulator U18. The output voltage ofU18 is set to 10.5. This 10.5 Vdc through a diode D4 drives the audio section of the 2028 VoIP. It is also fed into voltage regulator U19 and U20. The output voltage of U19 isset to 3.3 Vdc and this 3.3 Vdc is also fed into voltage regulator U16. The output voltageof U16 is set to 1.5 Vdc. The output voltage of U20 is set to 2.5 Vdc. The 3.3 Vdc, 2.5vdc, and the 1.5 Vdc powers the digital section of the 20-28 VoIP.5.2 Transmit AudioTransmit audio UDP packets from the Ethernet interface section are passed to themicroprocessor U8 for decoding. The decoded digital audio is then sent to the DSP U10.The DSP then converts the digital audio to analog and adjusts the level out. The audiois passed to pin 4 of J3 to the 20-28 VoIP Interface board where it is sent to pin 21 of theradio interface connector P1.The audio is also fed into the speaker driver U3. U3 and its associated circuitry is a wideband audio amplifier set to have a gain of 36 dB. The output of the speaker driver goesto pin 7 of J4 and sent to the 20-28 Interface board where it is sent to the speaker jackJ16.5.3 Receive AudioReceive audio from the radio comes from pin 1 of the radio interface connector P1. It isthen passed to pin 4 of J5 on the 20-28 VoIP board. The audio is biased by resistorsR126 and R136. The audio then passed through the DSP U10 where it is converted todigital. The digital audio is then sent to the microprocessor to be assembled in to UDPpackets. The UDP Packets are then passed to the Ethernet section.5.4 OutputsThe output states are controlled by U17 on the20-28 VoIP board. The outputs are thensent to the open collector output drivers U2 and U3 on the 20-28 VoIP Interface Boardvia J13. Outputs 9 and 10 are optionally connected to relay outputs by JP7 and JP8.18

5.5 Local ControlThe local control is done through the 20-28 VoIP Interface board. The local deskmicrophone is connected to J15, which is connected to J5 passing all connectionsdirectly to the DSP, U10 on the 20-28 VoIP board where the audio, PTT and monitorfunctions are processed. The intercom switch is connected to J4 which connects to theDSP. The local speaker audio is sent from the DSP to the audio amplifier U3 and thensent to J4 on the 20-28 VoIP Interface board where it is sent to J16, the speaker jack.5.6 MicroprocessorThe Net ARM 7520B MCU U8 provides the network interface functions and provides theplatform for the application code. Integrated peripherals include a 10/100 Ethernet MAC,two serial ports, and numerous general-purpose I/O pins. An RTOS and a TCP/IP stackare included along with drivers for the internal peripherals.5.7 Digital Signal ProcessorThe DSP U10 provides the audio processing functions. This DSP has six audio inputs,four audio outputs, a single Sigma-Delta CODEC, and an audio multiplexor to connectthe CODEC to one audio input and one audio output. It also has numerous generalpurpose I/O pins and a host interface. The DSP firmware comes pre-programmed inROM and the functions provided can be controlled by the host CPU U8 through the hostinterface. The DSP firmware provides the following standard CODEC algorithms: G.711,G.723.1, and G.726.5.8 Ethernet InterfaceThe Ethernet interface consists of a three port 10/100 Base-TX Switch U4. One port isconnected externally to the LAN and the second port is connected externally to acomputer to allow the computer access to the LAN. The third port is connected internallyto the Ethernet port of the NET ARM MCU U8. LEDs integrated into the Ethernetconnectors will provide Connect and Activity status. The Ethernet port for connecting tothe PC will be cross-wired to allow straight-through cables to be used on both ports.5.9 20-28 VoIP Interface BoardThe 20-28 VoIP Interface board provides the connections between the 20-28 VoIP boardand the radio, power, and local control components. Items not covered thus far aredescribed here. P1 pin 1 is the RX audio input. It is connected to J4 pin 5 on the 20-28VoIP board where it goes to the DSP. Transmit audio comes from the DSP and goes toJ3 pin 4 on the 20-28 VoIP Interface board and goes through impedance resistors to P1pin 21. P1 pin 25 is the COR input. It goes through Q3 to J2 pin 2 on the 20-28 VoIPboard then to the DSP. P1 pin 9 is the transmit indicator input. It goes through Q4 thento J11 pin 2 on the 20-28 VoIP board then to the DSP. P1 pins 2 and 3 are serial data inand out. The signals are selectable for RS485 or logic level by SW1. The signals go toJ8 pins 3 & 4 on the 20-28 VoIP board then to the Net ARM MCU.19

APPENDIX A - RADIO INTERFACESThis appendix contains instructions for interfacing the 20-28 VoIP panel for various radioapplications.Conventional Binary InterfaceThe following steps outline the procedure for interfacing a conventional radio requiringbinary control signals to the 20-28 VoIP:1. Identify which radio functions should be controlled by the 20-28 VoIP. Theavailable functions of the conventional binary interface on the 20-28 VoIP aredescribed below. COR: Control signal from the radio that is active while receiving audio.PTT: Control signal from the 20-28 VoIP that is active when the radio shouldtransmit.Channel Control Outputs: Control signals from the 20-28 VoIP to changethe channel on the radio through binary output patterns. The number ofoutputs used for channel control can be programmed from 1 to 8. Consultthe table below for the number of outputs required. Note that output #1 willalways be the least significant output. Outputs #2 to #8 not used for channelcontrol are available as user defined outputs.Number of ChannelMax. # of ChannelsOutputs12243841653266471288255User Defined Outputs: Several additional outputs are available forcontrolling other radio functions.2. Construct the cable end that will connect to the 20-28 VoIP's P1 Radioconnector. A generic cable kit is available from IDA Corporation (Part No. 102OPT371). The following table lists the connections required to a DB25 maleconnector for each 20-28 VoIP function.ConnectionPin #1Pin #7Pin #20Pin #21Pin #25Output #1-7User-programmableOutput #8Output #9Output #10FunctionRX AudioGround 13.8 VdcTX AudioCORChannel OutputPatternUser DefinedPTTUser Defined20

Conventional Binary Interface (cont.)3. Connect the other end of the cable to the radio. This may require modificationsto the radio. Consult the radio manual for details.4. Configure the jumpers on the 20-28 VoIP based on the system requirements.Check the audio level adjustments.Trunking Radio InterfaceThe 20-28 VoIP may also be interfaced to a trunking radio for transmit and receive onlywith no channel or scan control. Full featured, radio model specific interfaces areavailable, contact the factory. In order to provide handshake tones in a trunkingapplication, it is necessary to utilize the TRANSMIT INDICATOR input on the 20-28VoIP. The TRANSMIT INDICATOR input is on Pin 9 of P1. The 20-28 VoIP must alsobe programmed for the correct TX Active HI / LOW polarity under the RADIOPARAMETERS screen as shown above. It needs to remain active throughout the entiretransmission. For conventional applications it should be set to IGNORE.Additional Radio InterfacesFor radio specific interfaces, refer to the Radio Configuration Parameters screen of the20-28 VoIP or contact the factory for the availability of updates for additional radiointerfaces.21

PARTS LISTS20-28 VoIP Main 2627282930313233343536ReferenceDescriptionCAP, A ELEC 47UF 6.3C1,2,12,25,28,44,46CAP, A ELEC 1UF 50VC3,8CAP, A ELEC 47UF 16VC4,45C5,6,13,15,50,51,52,53,54,55, CAP, .1UF X7R ,119,121CAP, A ELEC 10UF 16VC7,11,17,18,20,21CAP, A ELEC 2.2UF 35C9CAP, .47UF Y5V 16VC10,120CAP, A ELEC 4.7UF 25C14,26CAP, A ELEC 470UF 25C16,37,38,42,48CAP, A ELEC 150UF 10C19,47CAP, .1UF X7R 16VC22,31,32,33,34CAP, 22PF NPO 50VC23,24CAP, 10PF NPO 50VC29,30,67,103CAP, .01UF X7R 10%50C35,39,40CAP, 2700PF X7R 50VC36CAP TANT, 1UF 35VC41,43CAP .22UF Y5V 16VC49CAP, .1UF X7R 16VC62DIODE, SWITCH BAS16D1,2,9,10DIODE, SCHKY B140D3,5DIODE, SCHKY B330AD4,7,8LED, SUPER RED 0603D6FUSE PC MOUNT 1 AMPF1JACK MOD, RJ45 LEDJ1RECEPT 36 SIP .1J2RECEPT 36 SIP .1J3RECEPT 36 SIP .1J4RECEPT 36 SIP .1J5JACK MOD, RJ45 LEDJ6CONN 36 POS R/A HDRJ7RECEPT 36 SIP .1J8CONN. 6 POS POSTJ9RECEPT 2 POS .1J10RECEPT 36 SIP .1J11SCKT, DIP, 16 PIN ICJ13FERRITE, 150 OHM 800L1,5,6,7,8,922Part 9.1110.14.1411.1116

626364656667686970717273747576777879POWER IND, 4

20-28 VoIP and in the Profile Configuration screen of the 24-66 VoIP. From a bandwidth standpoint, the Multicast protocol is a much more efficient method of transmitting audio . SW1 Position A is for logic level serial interface. Position B is for RS485 level serial interface. JP 5 IN for