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Will I be able to hear VHF and UHF signals on my DIgital Police Scanner?
My little city still uses the UHF and VHF signals, but the State Patrol uses Digital. If i buy the Digital scanner, can i pick up the old signals on there from my local departments.
Normally you cant on my scanner plus very illegal.
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Help me identify a bug in my house and yard. Any Entomologists out there?
I live in central NC and during the summer months we have one particular “bug” that chooses to inhabit our home. I know it’s not harmful – just creepy- but I can’t identify it. It has some characteristics of a roach – but I can’t find it any roach categories. It is about 2 inches long, black segmented body (2 segments), NO wings, long thin antennae, rounded head, 6 jointed legs, and the tail is short (almost nonexistent) with 4 “stubby” sections – two that point straight away from the body and two the point upwards. They are not hurting anything – but they are continually getting into my dogs food, and they are LOUD when they eat. I have looked online and tried many “bug identifiers” with no luck.
Any entomologists out there have an idea?????
Thanks for all your help!
Hmm.. Without a picture, it’s hard to make an accurate identification. Sounds like a Rove beetle to me. Please check out the below and see if that’s your wee beastie.
The main server is in the company office a few hundred feet away, the signal is sent around the property to several antennas that are used for our wireless inventory system, and I used to grab signal from that, recently they relocated one antenna from the building I am in to another building to gain signal in the yard, and my signal was lost. Also am inside a large steel building. I am looking at running an SMA cable approx 50-75 feet going thru the wall to an external antenna. Are there any limits to signal loss and cable length? Also what advantage would there be adapting from SMA to N type cable…would the signal be any better/worse on this cable? I don’t think a high gain antenna would help me get any better signal inside of this steel building. The boss is willing to buy what I need to reconnect, but we need to know what way to go.
SMA and N both refer to the type of connector on the end of the cable – not the cable itself. While some rf connectors are better than others I seem to recall N and SMA are similar.
Yes there are limits to how much signal loss is acceptable. 75 ft of cable can add quite a bit of loss when on the recieving end of a weak signal. The amount depends on the sensitivity of the wireless reciever you are using.
Good quality RF cable and high gain antennas aren’t cheap. There is no guarantee it will work reliably once set up. Are you sure it wouldn’t be cheaper to add another access point inside the building or hard wire stuff?
My problem: find the capacitance per unit length of three long coaxial metal tubes, with radii a < b < c . A wire connects the innermost and outermost tubes (radii a and c).
-> Put an arbitrary charge +Q on cylinders a/c and -Q on cylinder b, +Q on a and c is distributed in some unknown way, let’s call them Qa and Qc and similarly Qb = -Q.
-> C = Q/delta V. So find the potentials:
-> Correct me if I’m wrong here (I probably am): E-field for a
->delta V = integral of E dot dl. So V(a) = Qa/(2*pi*epsilon_o) * ln(a/b)? and V(c) = (Qa + Qb)/(2*pi*epsilon_o) * ln(b/c)?
-> V(a) should = V(c)…I somehow want to get this in terms of Qb/-Q/+Q/Q…not really sure how to work that out. I feel also like I have tons of error in my logic. Any help is greatly appreciated, thanks in advance.
you can ignore the center tube, it has no effect on anything, as long as it is thin compared to the other dimensions. It just floats there.
see the reference for formula for capacitance of a coaxial cable. The derivation is also shown.
