Paul Ramplebergh, in Belgium, is trying to use a scanner for precompliance. He's had some problems with the authorities there -- they don't want to let anyone have a scanner that could receive unlicensed frequencies. I have some problems with using an inexpensive scanner for compliance, but not for engineering and precompliance. Paul, I think, wanted to use his handheld scanner for precision measurement, which is a bit beyond them. That's _my_ view, anyway.
I've used several scanners for engineering and precompliance testing. Handheld scanners are much easier to carry out to an EUT than dragging an analyzer on a cart. Desk-type equipment such as Icom and the new AOR -- I'd love to have an AOR 5000 -- would be, IMO, more accurate. However, my objections to scanners run in these lines: 1. Amplitude accuracy is poor. In part, this is a function of the readout, and Paul was going to pull amplitude information out of his using the built-in computer bus. Even high-end scanners such as the Icom R7100 amplitude response varies with frequency; this must be accounted for when trying to get precision readings. Note that Icom 7000 and 7100 use separate, switched front ends for covering the frequency range, and each one must be individually aligned. 2. Bandwidth. I have had two Yupiteru 7100 handheld scanners,and the IF bandwidth (nominal 15 KHz) varied between the two units, with one having rather poor ultimate selectivity. I don't know what the FMBC bandwidth was, as I prefer to use AM mode in troubleshooting, but if it's 180 KHz, it's already a bit wide for EMC measurements. You'd read a bit high on broadband noise. My AOR 8000 is different (netter) yet. The AOR 5000 has the potential of being very useful as its filters may be switched independent of noise. When I get the money I may try one. 3. Inability to take QP. This is a bit of a quibble, the way I use scanners, but if you want to know how many dB you really need, then you'll want to wire in a QP detector. This will also call for disabling the AGC, as otherwise one would be taking the weighted average of a log function rather than of a linear reading. This begins to complicate things, hanging external detectors on the IF and could end up making the whole setup hard to handle. In this country, at least, its difficult ro buy a scanner which is rated to cover all the frequency ranges, with cellular being left out. While this is something people with technical expertise can circumvent, the current legislative climate in Washington may end up doing away with modifiable receivers completely. I don't want to start anything on the scanner/cellphone issue (please!) but I understand one telephone industry representative is urging legislation that would completely pot scanners in plastic to make modification impossible, Aaargh. Anyway... they're useful, No doubt about it. Beyond a certain point -- again, my opinion -- they become less useful. This could be remedied by modifications. One must then ask if a nice piece of surplus EMI gear would be considered more credible,in view of the limitations of consumer grade receivers. That's my two groschen anyway. Cheers, Cortland ====================== Original Message Follows ==================== >> Date: 09-Feb-97 16:01:11 MsgID: 1044-115610 ToID: 72146,373 From: moshe valdman >INTERNET:[email protected] Subj: frequency scanners Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Part 1 of 1 Sender: [email protected] Received: from ruebert.ieee.org (ruebert.ieee.org [199.172.136.3]) by hil-img -5.compuserve.com (8.6.10/5.950515) id SAA08901; Sun, 9 Feb 1997 18:57:26 -0500 Received: (from daemon@localhost) by ruebert.ieee.org (8.7.5/8.7.3) id RAA24645 for emc-pstc-list; Sun, 9 Feb 1997 17:16:20 -0500 (EST) List-Post: [email protected] Date: Mon, 10 Feb 97 00:08:42 PST From: moshe valdman <[email protected]> Subject: frequency scanners To: [email protected] X-Mailer: Chameleon V0.05, TCP/IP for Windows, NetManage Inc. Message-ID: <[email protected]> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII Sender: [email protected] Precedence: bulk Reply-To: moshe valdman <[email protected]> X-Resent-To: Multiple Recipients <[email protected]> X-Listname: emc-pstc X-List-Description: Product Safety Tech. Committee, EMC Society X-Info: Help requests to [email protected] X-Info: [Un]Subscribe requests to [email protected] X-Moderator-Address: [email protected] Hello again, I'm interested in the potential use of low cost scanners as "low end" receivers\spectrum analyzers. My problem is I don't know anything about how they work, what are the inherent limitations (freq accuracy, amplitude accuracy etc). I'm thinking of course ! about the synthesised ones where you don't have a xtal per each frequency. Can someone give a brief explanation or/and point me to some technical information (preferably on the web). thanks ------------------------------------- Name: moshe valdman E-mail: [email protected] List-Post: [email protected] Date: 02/06/97 Time: 00:29:57 This message was sent by Chameleon ------------------------------------- ----------End of Original Message---------- ====================== End of Original Message =====================
