radiated emissions go a bit lower.
§15.209 Radiated emission limits; general requirements.
(a) Except as provided elsewhere in this subpart, the emissions from an
intentional radiator shall not exceed the field strength levels specified in
the following table:
| Frequency (MHz) | Field strength (microvolts/meter) | Measurement distance
(meters) |
| 0.009-0.490 | 2400/F(kHz) | 300 |
| 0.490-1.705 | 24000/F(kHz) | 30 |
| 1.705-30.0 | 30 | 30 |
| 30-88 | 100** | 3 |
| 88-216 | 150** | 3 |
| 216-960 | 200** | 3 |
| Above 960 | 500 | 3 |
On Monday, August 12, 2019, 6:04:43 PM EDT, John Woodgate
<[email protected]> wrote:
A small point; the lowest carrier frequency is 153 kHz. Sidebands extend down
to 148 kHz. All the European LF and MF broadcasting carrier frequencies are
multiples of 9 kHz.
Best wishes
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK On 2019-08-12 22:21, Brent DeWitt wrote:
For the upper end; conducted measurements end where radiated emissions start.
Back in the mists of time someone decided that a ten meter wavelength was
something that could radiated fairly efficiently from cables, so radiated
emissions sounded like more of a risk to telecommunications.
The 150 kHz number is more directly related to licensed services. The limit
was 450 kHz in the US until harmonization with the European measurements. The
US limit was based on protection of the AM broadcast band. The European
Longwave AM band extends down to 148kHz, so I assume they simply rounded up to
150 kHz.
>From a practical standpoint, if you stick with a 50 uH LISN, it starts to
>deviate from 50 ohms quite a bit as you go lower.
Hope that helps.
Respectfully,
Brent DeWitt, AB1LF
On 8/12/2019 4:36 PM, [email protected] wrote:
Hello group,
Does anyone know why the conducted emissions for ITE products starts at
150KHz and end at 30MHz? Why not start at 120KHz or 190KHz. Why finish at 30
and not 40MHz?
Thank you Peter -
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