Difference between revisions of "Substation Kit - 1007102000"
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:* Frequency response: With the loudspeaker one should try to achieve a frequency response quite flat, but with a slight emphasis in the mid frequency area (around 800Hz). The frequency response is affected by the loudspeaker itself, and by the mechanical design of the station. | :* Frequency response: With the loudspeaker one should try to achieve a frequency response quite flat, but with a slight emphasis in the mid frequency area (around 800Hz). The frequency response is affected by the loudspeaker itself, and by the mechanical design of the station. | ||
| − | + | ||
| − | + | :*Chamber (the area behind the loudspeaker): The chamber can be a separate box behind the loudspeaker, or it can be the station housing itself. The shape and size of the chamber will influence on the sound from the loudspeaker. If the rear side of the loudspeaker is not acoustical shielded from the front, sound waves from the rear can affect the frequency response in the listeners spot. The chamber should if possible have rounded edges to prevent standing waves (resonance), and it should be filled with a sound absorbing material to further damp standing waves which will influence on the speaker diaphragm and so on the sound reproduction. A reason to use a separate box for the loudspeaker is to reduce the acoustical coupling between the loudspeaker and microphone. | |
| − | + | ||
| − | The mounting of the microphone is quite critical concerning: | + | :*The grille on the front plate is more a cosmetic issue as long as there are enough opening (approx. 50%). The grille should cover the loudspeaker area. |
| − | + | ||
| − | + | *The microphone. <br>The mounting of the microphone is quite critical concerning: | |
| − | + | ||
| − | + | :*Shielding: It should mechanically be shielded from the loudspeaker. This is done by mounting it in an absorbing material, and if possible not directly to the same front plate as the loudspeaker. | |
| − | + | ||
| + | :*Frequency response: The microphone should also be mounted as close to the front plate as possible. The space between the split in the front plate and the microphone can affect the frequency response. Also the split (or splits) should be longer than the diameter of the microphone. With the 1321-board and 1425-board the microphone is already mounted. | ||
| + | |||
| + | *Non-linear effects: There must be no loose parts that can vibrate as this will cause distorting sound. A simple measurement method is to do a frequency sweep with quite loud volume, and then listen do detect problems. | ||
| + | |||
| + | *Acoustical coupling: If the acoustical coupling between the loudspeaker and microphone becomes to high the duplex algorithm in the exchange will not have an optimal performance. You should try to place the microphone and loudspeaker as far apart as possible. To verify that the duplex will function acceptable one should do a counting test (the person at one of the locations says ‘One’, the person at the second location says ‘Two’ etc.) and if possible with some background noise. | ||
| + | |||
| + | *To do a really good acoustical design requires much work and experience. The most important criteria is of course the subjective: To fulfill the customer’s needs. | ||
Revision as of 15:55, 24 June 2008
- 1007102000: Substation.
Consisting of 1307-substation board, plastic loudspeaker, electret microphone and tamperproof button.
Contents
1307 Substation Board
Features
This kit includes: The 1307-station board, nylon screws and spacers, CE-labels and packaging.
The 1307-station board features:
- Connector for external microphone
- Connector for 2 buttons (ID and ID+M)
- Volume control
- Connector for status LED
- Connector for loudspeaker
Electrical details
- See schematics in appendix D.
- The microphone gain is adjusted by potentiometer RP1.
- The loudspeaker volume is adjusted by potentiometer RP2
Connecting loudspeaker and microphone:
| Connector-pin | Function |
|---|---|
| J4-1 | Electret microphone (positive) |
| J4-2 | Electret Microphone (negative) |
| J4-3 J4-4 |
Loudspeaker, no volume control |
| J4-2 J5-2 |
Dynamic close talk microphone |
| J4-5 J5-1 |
ID+M-button |
| J5-3 J5-4 |
M-button |
| J6-1 | D-branch |
| J6-2 | C-branch |
| J6-3 | B-branch |
| J6-4 | A-branch |
| J7-1 J7-2 |
Connection of loudspeaker with volume control. |
| J7-3 J7-4 |
Connection of status LED. J7-3 Positive, J7-4 negative. Must be connected or shorted to make microphone work |
The shunt S1 is for PRIVATE/OPEN. Shorted = PRIVATE, Open = OPEN (Default)
Mechanical mounting
The circuit board should be mounted with the nylon screws and spacers due to ESD protection. You can use weld nuts with the size of M3.0x5.0x6.0 fastened to the front plate for the screws.
See Figure 1-1 for dimensions.
Loudspeaker (waterproof) w/cables
This kit includes: 63 ohm 1W loudspeaker, fastening plate, ESD-shield, screws, nuts, 0,3m cable and vliseline (dark gray and white). Se Error! Reference source not found. for mounting.
Electret microphone w/mounting
This kit includes: Condencer microphone and absorbing baffle.
Se chapter 1.1 for mounting considerations.
Tamperproof button
This kit includes: Tamperproof button, wire.
To mount the button, drill a hole in the front plate with diameter 20mm. The button will build 25mm into the station.
Acoustical Considerations
The most important acoustical issues to be aware of when designing a new station is:
- The loudspeaker.
- Frequency response: With the loudspeaker one should try to achieve a frequency response quite flat, but with a slight emphasis in the mid frequency area (around 800Hz). The frequency response is affected by the loudspeaker itself, and by the mechanical design of the station.
- Chamber (the area behind the loudspeaker): The chamber can be a separate box behind the loudspeaker, or it can be the station housing itself. The shape and size of the chamber will influence on the sound from the loudspeaker. If the rear side of the loudspeaker is not acoustical shielded from the front, sound waves from the rear can affect the frequency response in the listeners spot. The chamber should if possible have rounded edges to prevent standing waves (resonance), and it should be filled with a sound absorbing material to further damp standing waves which will influence on the speaker diaphragm and so on the sound reproduction. A reason to use a separate box for the loudspeaker is to reduce the acoustical coupling between the loudspeaker and microphone.
- The grille on the front plate is more a cosmetic issue as long as there are enough opening (approx. 50%). The grille should cover the loudspeaker area.
- The microphone.
The mounting of the microphone is quite critical concerning:
- Shielding: It should mechanically be shielded from the loudspeaker. This is done by mounting it in an absorbing material, and if possible not directly to the same front plate as the loudspeaker.
- Frequency response: The microphone should also be mounted as close to the front plate as possible. The space between the split in the front plate and the microphone can affect the frequency response. Also the split (or splits) should be longer than the diameter of the microphone. With the 1321-board and 1425-board the microphone is already mounted.
- Non-linear effects: There must be no loose parts that can vibrate as this will cause distorting sound. A simple measurement method is to do a frequency sweep with quite loud volume, and then listen do detect problems.
- Acoustical coupling: If the acoustical coupling between the loudspeaker and microphone becomes to high the duplex algorithm in the exchange will not have an optimal performance. You should try to place the microphone and loudspeaker as far apart as possible. To verify that the duplex will function acceptable one should do a counting test (the person at one of the locations says ‘One’, the person at the second location says ‘Two’ etc.) and if possible with some background noise.
- To do a really good acoustical design requires much work and experience. The most important criteria is of course the subjective: To fulfill the customer’s needs.