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View Full Version : Yet another Industrial App



TomS
03-15-2009, 09:13 PM
This seems to be the week for showing off our industrial apps so here's mine. It's a RF detector with dynamic range of 60 dB and a usable frequency range of 50 MHz to 2 GHz. It is temperature compensated. The interface is IP based and utilizes a XPortAR. I'm also using Power over Ethernet to provide the +3.3V needed by my circuit. Not shown is the custom extrusion it's housed in. I work in the broadcast industry and my device measures the power level of TV & FM signals through transmission line(s) to the antenna. Power levels range from 100 W to 200 KW.

Tom

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Tom

Peter Jakacki
03-16-2009, 09:28 AM
Very professional looking pcb and layout there Tom. It looks like the top pcb might be a commercial module from RFD perhaps or is it one of your own? How about the control board, is it multilayer and do you have a special pcb program to handle the RF side such as the extra via etc? That looks like a very small transformer for the LTC4267, what is the spec on that? It's opto is really small too, I don't think I have seen them that small.

It shows that there are a lot of lurkers (effectively) on this forum that are doing some serious stuff! BTW, putting aside the technology I also consider 200 kW RF to be some pretty serious stuff http://forums.parallax.com/images/smilies/smhair.gif

*Peter*

Timothy D. Swieter
03-16-2009, 09:43 AM
Way cool! Very, very nice looking layout. I have been reading a lot about Power Over Ethernet lately and was thinking about a design that may use it.

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Timothy D. Swieter, E.I.
www.brilldea.com (http://www.brilldea.com) - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
www.tdswieter.com (http://www.tdswieter.com)

mctrivia
03-16-2009, 01:20 PM
I looked into power over Ethernet but it is not compliant with gigabit switches

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Need to make your prop design easier or secure? Get a PropMod (http://propmodule.com) has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.

dMajo
03-16-2009, 05:10 PM
mctrivia said...
I looked into power over Ethernet but it is not compliant with gigabit switches


That's not true:
3Com® OfficeConnect® Managed Gigabit PoE Switch (3CDSG10PWR)[ITA (http://www.3com.com/prod/it_IT_EMEA/detail.jsp?tab=features&sku=3CDSG10PWR)] [ENG (http://www.3com.com/products/en_US/detail.jsp?pathtype=purchase&tab=features&sku=3CDSG10PWR)]
I am sure because I own two and together with·five "3Com® IntelliJack® Switch NJ220 (http://www.3com.com/prod/it_IT_EMEA/detail.jsp?tab=features&sku=3CNJ220-CRM-20)" forms the network structure in my domotic home (multiroom/multimedia, voip, internet, remote video-security and home automation control...)

BTW: the difference between fast-ethernet(100M) and gigabit-ethernet is that the last one utilizes all the RJ45 wires. PoE is a DC power supply above which is superimposed the differential (AC) communication. This can be done on all four twisted pairs as noted on XPortAR datasheet (I also use this beast even if it is not so cheap - next todo: invest some money in their SDK so that I can customize the firmware)

Cheers

Timothy D. Swieter
03-16-2009, 05:19 PM
And I read that the POE standard is going through revision for higher power levels too - maybe it already has. I can't recall if the article I read was months old or newer.

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Timothy D. Swieter, E.I.
www.brilldea.com (http://www.brilldea.com) - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
www.tdswieter.com (http://www.tdswieter.com)

TomS
03-16-2009, 07:17 PM
Peter, The top pcb is my design. The substrate is Rogers 4350B and I've achieved a return loss greater than 30 dB to 900 MHz. Which is dammed good if I do say so. The main board is 4-layer and I used EAGLE to layout both boards.

The transformer is a standard made by Coilcraft for PoE. I really hate to think about custom transformers for medium to small size projects so Coilcraft saved the day. The specific model I'm using is a POE30P-33L_. See these links for more info;

http://www.coilcraft.com/prod_poe.cfm

and

http://www.coilcraft.com/poe_ep.cfm

The optoisolator is a PS2911.

200 KW is for mutiple TV xmtrs feeding a combiner and then split into two equal 100 KW signals in 8 inch line feeding a common antenna.

Timothy, I love PoE. It makes power distribution a snap. And yes, it will be able to handle double the maximum power of the original spec soon. You may have to wait a while for switch manufactures to catch up though you could always build your own power insertion device.

dMajo, You're right about the price being high but it was the only device I could find at the time with PoE capability. I could have used a xfmr but the total size was too great.

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Tom