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Preliminary Release 

Alligator Communications Model 2788 Technical Manual REV2.3                Copyright © 2019 

Page 6

 

 

1.3   Technical Specifications 

 

GENERAL 

 

Frequency 

 

787-788  MHz

 

Input Voltage

 

10-24 Vdc

 

Current Consumption (at 13.8 Vdc)

 

<80 mA

 

     Receive Mode

 

100 mA

 

     Transmit Mode (0.2 Watts)

 

< 0.5 A

 

Data Rate 

9600 bps to 38.4 kbps 

Connectors

 

 

     Antenna

 

Type N female 

     Power

 

2-pin Captive, Rectangular 

     Data (RS-232)

 

DB9F 

Environment

 

 

     Temperature

 

-30°C to +50°C 

     Humidity

 

95% at 40°C 

Dimensions

 

6.75” x 1.5” x 5.75” 

Weight

 

2 pounds 

 

 

Summary of Contents for 2788 MAS

Page 1: ...Preliminary Release Alligator Communications Model 2788 Technical Manual REV2 3 Copyright 2019 Page 1 Model 2788 MAS Ethernet RS 232 UHF Radio Transceiver Technical Manual ...

Page 2: ...Preliminary Release Alligator Communications Model 2788 Technical Manual REV2 3 Copyright 2019 Page 2 REVISION HISTORY REV DESCRIPTION DATE 1 Initial Release 10 15 2018 ...

Page 3: ...5 219 1 7 RF exposure information9 2 0 Radio Configuration and Operational Check10 2 1 General Discussion10 2 2 Operational Bench Test10 2 2 1 Antenna Connector10 2 2 2 Power Connector11 2 2 3 Initial Checkout11 3 0 Field Configuration and Verification15 3 1 15 4 0 Front Panel Indicators17 5 0 User Configuration and Diagnostic Menu18 5 1 18 5 2 18 5 3 18 5 4 19 5 5 19 5 6 19 5 7 19 5 8 19 5 9 20 5...

Page 4: ...Address22 5 25 Remote RTU1 MAC Address23 5 26 Master RTU MAC Address Table23 5 27 Host MAC Address Table23 5 28 High QOS Quality Of Service IP Address Table23 5 29 Loopback Remote MAC Address24 5 30 Diagnostic Tests24 5 31 Display Status Screen25 5 32 Display RTU Table25 5 33 Display Host Table25 5 34 Display QIP Table25 6 0 Theory of Operation26 6 1 RS 232 Communications26 6 2 Ethernet Communicat...

Page 5: ...CC rules Parts 27 and 90 The 2788 data radio is frequency synthesized and programmable to individual transmitter and receiver frequencies in the 757 and 788 MHz frequency band The transceiver is a fixed channel half duplex radio available with a channel bandwidth of 12 5 kHz and up to 100 kHz It interfaces with both Ethernet and RS 232 1 2 Applications The 2788 data radio is designed for point to ...

Page 6: ...uency 787 788 MHz Input Voltage 10 24 Vdc Current Consumption at 13 8 Vdc 80 mA Receive Mode 100 mA Transmit Mode 0 2 Watts 0 5 A Data Rate 9600 bps to 38 4 kbps Connectors Antenna Type N female Power 2 pin Captive Rectangular Data RS 232 DB9F Environment Temperature 30 C to 50 C Humidity 95 at 40 C Dimensions 6 75 x 1 5 x 5 75 Weight 2 pounds ...

Page 7: ...ion 4GFSK Symbol Rate 4800 Hz Data Rate 9600 bps Maximum Frequency Deviation 2400 Hz Attack Time 1 msec Release Time 0 5 msec Bandwidth 6 25 12 5 25 or 50 kHz RECEIVER Input Sensitivity 117 dBm at 10 6 BER Impedance 50 Ohms Frequency Range 757 758 MHz Frequency Step Size 1 Hz Frequency Stability 1 ppm Selectivity 100 dB Desensitization 60 dB Intermodulation 75 dB EIA Spurious Image Rejection 80 dB...

Page 8: ...d shall be in lieu of any other remedy available by applicable law All returns to the factory must be authorized by the SELLER prior to such returns Upon examination by the factory if any instrument is found to be defective the unit will be repaired and returned to the BUYER with transportation charges prepaid by the SELLER This warranty does not apply to equipment which in the opinion of the SELL...

Page 9: ...is equipment In accordance with FCC Rules Section 15 21 the user of this equipment is advised that changes or modifications not expressly approved by the party responsible for compliance could void the user s authority to operate the equipment 1 7 RF exposure information FCC Rule Section 1 11307 and Industry Canada RSS 102 regulations contain limits on human RF exposure from transmitters To meet t...

Page 10: ... prior to installation at the desired site it is highly recommended that the following tests be performed in sequence Please refer to 2 2 3 Initial Checkout 2 2 1 Antenna Connector The 2788 radio antenna port RF Connector is a coaxial female Type N connector This connector mates with a male cable connector Type N such as Amphenol 3900 Andrew L44N or MIL Type UG 21 Under most circumstances bench te...

Page 11: ...and receiver settings of the 2788 radio 1 Connect a 50 Ohm dummy load to the antenna Type N connector The dummy load must have a power rating of at least 5 Watts Always insure that a load or antenna is connected to the Type N connector before DC power is applied 2 Connect a spectrum analyzer to the dummy load through a power attenuator 30 dB recommended 3 Connect a computer to the 2788 using a CAT...

Page 12: ...default IP address and port for the 2788 is 192 168 1 128 port 23 Below shows a typical puTTY configuration for communicating with the 2788 on IP default address 192 168 1 128 port 23 Be sure to have your computer IP address set in the subnet range puTTY should have Terminal set for local echo on For example below the computer has an IP address of 192 168 1 2 and communicates via Telnet to the 278...

Page 13: ...Manual REV2 3 Copyright 2019 Page 13 7 Open a Telnet session with the 2788 You should get a menu showing the current 2788 status and configuration Fig 2 You may end a Telnet session at any time by entering q The menu can be re displayed by either entering CR or ESCAPE ...

Page 14: ...gnal strength in dBm b Connect two 2788 radios together using suitable attenuators and coaxial cable Configure one radio to be a master om 1 CR to send test packets dt 3 and the other to be a remote om 0 to receive test packets dt 4 CR The receiver will monitor the number of good and bad test packets received in this one way test c Connect two 2788 radios together using suitable attenuators and co...

Page 15: ...ign a different Telnet port from the default port 23 For example tnp 50000 CR If you change the Telnet port you lose the session and must reconnect on the newly assigned port number with puTTY 6 Assign a group code if desired to identify a unique group of radios This blocks accidental communications with other 2788 radios For example gc 3 CR 7 Decide if the 2788 is a master or remote There is only...

Page 16: ...m 1 must contain a list of all RTU MAC addresses up to 512 Enter an RTU address using the following command rtu abc CR where abc is a lower case hexadecimal number from 000 to 1ff 0 to 511 decimal Enter rtutable CR to display the RTU table on a 2788 radio configured as a master om 1 12 When using remote RTU forwarding fm 0 or fm 2 the remote 2788 radio om 0 contains a list of up to 2 RTU MAC addre...

Page 17: ... up to 32 case sensitive characters It is entered with the command aesp CR The phrase is converted into a 256 bit key using the SHA256 secure hashing algorithm This key is used by the AES256 encryption and decryption algorithms 15 Should it be necessary the transmitter can be disabled with the command et 0 CR To re enable the transmitter et 1 CR 4 0 Front Panel Indicators The six front panel LEDS ...

Page 18: ... parameters are unchanged See Fig 3 5 1 Transmitter Frequency The transmitter frequency is set in MHz with up to 9 significant figures The allowed frequency range is from 757 to 788 MHz The full format is tf CR The decimal point is optional Trailing zeros are optional Examples 757 CR 757 0 CR 757 1 CR 757 12 CR 757123456 CR 5 2 Receiver Frequency The receiver frequency is set in MHz with up to 9 s...

Page 19: ...ystems there are 16 unique group codes to distinguish 2788 groups ranging from 0 to 15 The default group code is 0 gc CR Examples gc 0 CR gc 1 CR gc 15 CR 5 7 IP Address Each 2788 radio must be assigned a unique IP address within its LAN subnet group This permits both local and remote access of radio configuration and status information The default IP address is 192 168 1 128 It must be changed pr...

Page 20: ...CR Examples dr 1200 CR dr 2400 CR dr 4800 CR dr 9600 CR dr 19200 CR 5 12 Anti streaming Timer The transmitter key on time is timed to prevent disrupting the channel The maximum on time is the anti streaming time defined in seconds The default is 120 seconds This is most often invoked when performing testing with a CW carrier that is activated remotely ast CR Examples ast 120 CR ast 9999 CR 5 13 Te...

Page 21: ...R ep 1 CR 5 18 ID Identification Number When password entry is enabled ep 1 this ID must match to gain access to the 2788 The ID is case sensitive and can be any set of up to 16 characters including letters numbers and punctuation marks The default id is admin id CR Examples id CR id admin CR 5 19 Password When password entry is enabled ep 1 this password must match to gain access to the 2788 The ...

Page 22: ...tion MAC address 4 All No filtering all packets forwarded fm CR The factory default is fm 3 but it is highly recommended that it be changed to fm 1 host forwarding to prevent flooding Host filtering is easily done by entering the host MAC address in the host and remote 2788 radios At the master only host sources are forwarded At the remote only host destinations are forwarded Up to 16 host MAC add...

Page 23: ... either the master or remote radio is in forwarding mode 0 or 1 Up to 16 host MAC addresses may be saved in the host address table Both host number 0 to f and associated MAC address are in hexadecimal The table is initially cleared to all zeros Normally the table is filled starting at 0 and progressing to a maximum number of f The entire table is scanned for each forwarding operation by the master...

Page 24: ...2788 radios are currently assigned to MAC addresses starting with 70 b3 d5 9c e lb CR Example lb 70 b3 d5 9c e0 00 5 30 Diagnostic Tests There are several different diagnostic tests that can be performed using the dt command 1 TX CW 2 RX CW 3 TX 1 Way 4 RX 1 Way 5 TX 2 Way 6 Display TX Buffer 7 Display RX Buffer 8 Display TX and RX Buffers 9 Display Sub packet Types dt CR Note that ESC terminates ...

Page 25: ...displayed by two methods ESC a single press of the escape key CR CR a double press of the carriage return ENTER key 5 32 Display RTU Table The entire 512 entry RTU table is displayed rtutable CR 5 33 Display Host Table The entire 16 entry host table is displayed hosttable CR 5 34 Display QIP Table The entire 16 entry QIP table is displayed qiptable CR ...

Page 26: ...arding screening test Packet forward screening is done to minimize data traffic not intended for the radio network that could otherwise flood the system The 2788 has four programmable forwarding modes 1 No Screening 2 Host Screening 3 RTU Screening 4 RTU and Host Screening The simplest forwarding mode does not screen any packets This is referred to as the IP promiscuous mode and is only used in sm...

Page 27: ...o visibility to the host and or a separate client host for radio configuration and diagnostics Users of RS 232 interfaces also use the Ethernet interface with a Telnet client program The Telnet communications over the RF link shares the bandwidth of the system transparently 6 2 3 Graphics Heavy Communications The use of communications carrying a large amount of graphics data is discouraged Please ...

Page 28: ...mmunications Model 2788 Technical Manual REV2 3 Copyright 2019 Page 28 Figure 1 2788 Typical SCADA Block Diagram RTU 1 Internet Remot e Radio Master Radio Bastion Host Compute r RTU 2 Diagnos tic Comput er Etherne t LAN Etherne t LAN ...

Page 29: ...Preliminary Release Alligator Communications Model 2788 Technical Manual REV2 3 Copyright 2019 Page 29 Figure 2 2788 User Line Commands ...

Page 30: ...Preliminary Release Alligator Communications Model 2788 Technical Manual REV2 3 Copyright 2019 Page 30 Model 2788 Internal Reset Push Button Location ...

Page 31: ...is equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instructions may cause harmful interference to radio communications However there is no guarantee that interference will not occur in a particular installation If this equipment does cause harmful interference to radio or television reception which can be determined by turning th...

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