Helicopter airborne electronic equipment spread spectrum data link modulation and demodulation system SP-1400 working principle - D
Helicopter airborne electronic equipment spread spectrum modulation system SP-1400 virtual instrument tester design - 5
Written by: He Jun
. Overview:
"Helicopter airborne electronic equipment spread spectrum data link modulation and demodulation system SP-1400" is a data link modulation subsystem manufactured by the company "ELMER". The purpose of the
spread spectrum data link modulation and demodulation system SP-1400 subsystem is to provide transmission and reception of audio and serial data communications using spread spectrum (SS) modulation technology to ensure a high degree of communication privacy, noise interference and intentional signal interference. Interference (anti-interference ability). The
SP-1400 subsystem can be associated to two different UHF transceiver devices, capable of operating SS modulation mode; only one data transmission device (DTE) can be interfaced, while two different audio users can be connected, making the two completely independent channels can run simultaneously.
It should be pointed out that due to the wide baseband switching (70MHz), the related radio equipment should work within the UHF frequency band.
This chapter includes a description of the SP-1400 subsystem, unit integration including details on the data link control panel SP-1230 and the mounting tray MT-1120 unit.
also includes a description of the spread spectrum acoustic data modem SP-1212 unit; it also contains a basic description of spread spectrum principles and applicable methods.
"Helicopter airborne electronic equipment spread spectrum data link modulation and demodulation system SP-1400 virtual instrument tester" is used to detect and test "airborne electronic equipment spread spectrum data link modulation and demodulation system SP-1400" each For equipment with technical indicators, the testing program is written in accordance with the Helicopter Maintenance Manual "23-16-97".
"Helicopter airborne electronic equipment spread spectrum data link modulation and demodulation system SP-1400 virtualization instrument tester"
The system connection is as shown in the figure:
Helicopter airborne electronic equipment spread spectrum modulation system SP-1400 virtualization instrument test Device design - 5
Helicopter airborne electronic equipment spread spectrum data link modem system SP-1400 working principle - D
spread spectrum data link modem subsystem SP-1400 technical manual
Chapter 2 Operation
.1. Introduction:
This chapter contains the operating instructions, information, and procedures necessary to enable operators to effectively use the Spread Spectrum Data Link Modem Subsystem SP-1400 to accomplish their assigned tasks.
In order to describe the relationship between the operator and the equipment, this chapter is divided into the following paragraphs:
2.2, Operating functions
2.3, Controls and indicators
2.4, Operating procedures
Paragraph 2.2 describes the operating facilities and gives the general Subsystem application information.
Paragraph 2.3 describes the control indicators and protective devices by the name of the panel marked on the equipment; the location and operating function of each control and normal operating function.
Paragraph 2.4 is presented in table form or, if there are multiple options, a logical sequence diagram. The structure includes a brief explanation of the operation to be performed, the sequence of operations, and the visual or auditory observations resulting from the operator's actions.
.2. Operating functions:
The spread spectrum data link modem SP-1400 allows the execution of spread spectrum UHF band transceiver carrier frequency transmission of audio and data information. The SF-1400 is equipped with two independent spread spectrum modem SP-1212 units,
spread spectrum modem SP-1212 unit N.1:
spread spectrum modem SP-1212 unit N.2:
allows the establishment of two independent communication channels . Two different users can take advantage of the capabilities of the SP-1400 subsystem, allowing full control via a single control panel SP-1230 unit.
A transceiver/modem combination selector allows activating two interfaced UHF transceiver devices and two modem SP-1212 units, or enabling only one data terminal device.
Enables input/output processing of the audio communications device if CONV or SSV mode is selected.
If CONV mode is selected, the spread spectrum modem unit is bypassed and the audio device directly interfaces with the associated UHF transceiver to perform normal operation.
If SSV mode is selected, the spread spectrum modem SP-1212 unit is included in the receive/transmit audio processing chain, allowing "VOICE" voice spread spectrum modulation of the RF carrier signal.
SSD mode selection allows enabling spread spectrum modulation/demodulation of serial digital data by setting up a communications channel consisting of: a selected UHF transceiver (RT1 or RT2), the spread spectrum modem SP-1212 unit consists of the transceiver/modem Selector-enabled data terminal equipment pairing using the SP-1212 unit. The
operator can also monitor some basic functions of the SP-1400 subsystem, namely: modem startup conditions, encoding synchronization, ongoing transmissions, ongoing data modulation. The spreading code can be preset by two independent four-digit thumb wheel selectors. The
data band rate selection (120012400) is available via a switch located on the mounting tray MT-1120.
.3, controllers and indicators:
Figure 2.1, data link control panel:
The operation of the SP-1400 subsystem is controlled by the device located on the data link control panel SP-1230 unit. Figure 2-1 shows the SP-1230 front panel equipment described in Table 2-1.
Logo in the picture:
1), code selector, modem 2
2), sync indicator light, modem 2
3), Tx indicator light, modem 2
4), data indicator, modem 2
5), RT2 mode selector, modem 2
6), ON Indicator light, modem 2
7), transmitter/modem selector
8), ON indicator, modem 1
9), RT1 mode selector, modem 1
10), data indicator, modem 1
11), Tx indicator light, modem 1
12), sync Indicator light, modem 1
13), code selector, modem 1
14), code selector cover locking screw
SP-1230 front panel as described in Table 2-1 Device-1:
SP-1230 front as described in Table 2-1 Panel Device-2:
Mounting Tray MT-1120 unit is equipped with semi-operational controls {with rate selector) that cannot be used in normal operating procedures.
data rate preset glitches (Volume 2) See Chapter 6 of this technical manual.
SP-1230 front panel devices described in Table 2-1:
Reference FIG. 2-1 | Control or Indicator | Description | Function |
1 | - | Four-digit thumb wheel selector | They allow presetting modem No.2 spreading code. |
2 | SYNC | The green light | lights up when modem No.2 receives and acquires the synchronization phase. |
3 | Tx | Amber light | It lights up when Modem No.2 is in transmit mode. |
4 | DATA | Amber light | It lights up when modem No.2 is transmitting data. |
5 | RT2 | Three position rotary selector | It allows to select the working mode of modem No.2 and transceiver No.2 as follows: CONV: The traditional working mode has no spread spectrum modulation process, so modem No.2 is turned off. SSV: Select the spread spectrum modulation mode for voice communication. SSD: Select the spread spectrum control mode of data communication. |
6 | M2 ON | Green light | When modem No.2 is powered on, it lights up because mode SW or SSD is selected. |
7 | - | Three position rotary selector | It allows to select the transceiver, the modem combination is as follows: RT1/M1, RT2/M2: Modem No.1 is associated with transceiver No.1, Modem No.2 is associated with transceiver No. 2 is associated. RT1/M2: Modem No.2 is associated with transceiver No.1. |
8 | M1 ON | green light | RT2/M1: Modem No.1 is connected to transceiver No.2. |
9 | RT2 | Three position rotary selector | It allows to select modem No.1 and transceiver No.1 mode as follows: Regular working mode, the spread spectrum modulation process is not performed, so the modem. No.1 is closed. SSV: The spread spectrum modulation mode for voice communication is selected. SSD: Spread spectrum modulation mode selected for data communication. |
10 | DATA | Amber light | It lights up when modem No.1 is transmitting data. |
11 | TX | Amber light | It lights up when Modem No.1 is in transmit mode. |
12 | SYNC | The green light | lights up when modem No.1 receives and gets the sync phase. |
13 | - | Four-digit thumb wheel selector | They allow presetting the modem No.1 spreading code. |
14 | - | Electric screw | It is used to close and tighten the M1 and M2 address protective covers to avoid accidental code changes. |
