Reduce Inductance

It is more probable that 'the signal becomes more attenuated with increasing frequency as a result of the characteristic impedance of the transmission cable', rather than what is suggested.

One option is to convert to a medium that offers a higher transmission speed, like fibre-optics.

Another option is to change the transmission signal cable to a type that offers higher frequency transmissions with less attenuation.

Another option is to reduce the length of the transmission cable.

Another option is to reduce the frequency of transmission. In most industrial processes, anything that happens faster than 1 second is unreal, and best filtered/ignored.

Piggybacking a high frequency signal on transmission lines not designed for such signals is not a really good approach. Unless you can change the physical parameters of your power cable I don't recommend ever going that route.

From my own experience with such systems my recommendation to you is look at some prior work in that area. Why reinvent the wheel when you can use what is already available and adapt it to your own needs.

There are various products produced by chip manufacturers that are designed to transmit data across power lines.The fundamental part of their design is that they transmit during the zero cross of the line voltage. Everything else is signal and data handling. Basically the distance of transmission along the power lines is inversely proportional to the bandwidth of your data. Add data redundancy and/or error correction and you can get very good effective transmission distances.

If you really have to use a high frequency signal and your power requirements are very low power then you could just use a coaxial cable as your power line. By using an isolation transformer at each end for injecting and extracting the signal while sending DC power between the central conductor and shield (gnd). For higher power applications you could go with ladder line but be warned that things could get very ugly very quickly depending on what you are trying to accomplish.

you can reduce indctance by adding capacitor of suitable value . The formula is

lp= 1/cp

where l is the inductance in henry and c is the capacitor and p is the frequency in hertz.

If you are planing on developing a remote thermometer that transmits it's data via power lines the best technology to use is X10. Below is a link with some basic information:

http://en.wikipedia.org/wiki/X10_(industry_standard)

Although this standard has been around since the mid '70s it still suffers from many problems. You might want to consider newer much better ways to send data from a remote sensor: Wireless via ZigBee, Z-Wave, MiWi or wired via Ethernet, CAN, etc. I hope this helps!

You have not gave us enough information;

How fast is this temperature changing? Are you reading the temperature change of an explosion? the weather? some type of furnace?

What is the 'Thermometer' using for temperature measurement? thermocouple? thyristor? what?

What distance are you sending this signal?

What is the environment?

Most temperature measurement is in analog and converted to digital then through software back to a readable chart, log or maybe a database?

Give more information and we can help you meet your requirements or offer a variable option.

your question is vague.

what inductance will take place? rmote thermometer signal or in the cable?

generally character resistance will be 50, 75 or 100ohm for a coxcable. match it with relative resistor or something to it when transmitting.

Please explain what coupling method you are using and the frequency at which it's transmitting. And, if by power you mean DC power, then is it shielded and grounded at some end?

Hello gentlemen!

To be honest I was some confused as couldn't get a base point of discussion. Who did say you (us) that main trouble to cope with --- is an inductance? It's recognized fact the main foe to transmit a signal over wired network is a capacity of one. It does no matter is it communication net either power grid. Look behind your PC and you might see a twisted pair. Why wire been made this way?

Yes the power transformer(s) which terminate power-line has significant inductance but it does not affect for considered issue. Transformers only physically restrict range of transmitting, believed to be not longer than some neighbor buildings.

There had been said that thermometer is digital. It makes assumable to transmit code. And I agree there are a lot of decisions and companies offered reliable ways to transmit a signal over any network by anyway CODED , power grid include. But just coded one as here we can fight off entropy and dump a noise.

On other hand at topic of discussion there had been written "on increasing the frequency of transmitting my temperature signal the inductance increases" . I suppose this statement had directed discussion on wrong way as well. As here is possible to assume that developer intends to use somewhat analogue measurement technique when measured value connected with parameter (frequency). Otherwise why developers needs to change a frequency? In any case I do dare to admit that it is not the best technique to transmit signal for long distance through a line not suitable for it.

So we need here additional information. What's meant digital thermometer and what kind of applied measuring and transmitted technique.

By the way you can google this issue and find that even some ISP (internet providers) had studied this issue to deliver "last mile" through power line. ADSL for power grid, why not?

I agree with comment, that problems should be formulated more accurately regarding to the signal frequency can't change inductance(capacity). Increasing frequency can only gain adversing affect of ones.

Any way here is plausible to use good isolated code transmitter (modem, factory- or handmade) and if it needs repeators along line. Analogue(parameter) technique for data transmitting is barely applicable here.

Sorry for so long post.

Warmest regards.