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| To: | <[email protected]> |
|---|---|
| Subject: | Re: LF: Extension of the UK's 500kHz NoVs |
| From: | "Graham" <[email protected]> |
| Date: | Tue, 23 Dec 2008 21:13:41 -0000 |
| Importance: | Normal |
| In-reply-to: | <898BBB3308504B42A22405C10167B13A@acer5gi5q0ubzj> |
| References: | <898BBB3308504B42A22405C10167B13A@acer5gi5q0ubzj> |
| Reply-to: | [email protected] |
| Sender: | [email protected] |
John,This is my own observations on the proposal detailed, based on my use and expectations of the experimental licence. Increase to +10 dBW From my own point of view I would find such power levels unnecessary,firstly from the safety point of view, Initially the estate boundary field levels are calculated at 100mW erp the increase to 1 watt erp may of taken up any slack in the calculations but compliance at 10dBw within a 'normal' location may prevent successful licence applications in the future and if applicable retrospectively may result in the loss of the facility ? Operating from a normal installation the power levels required to establish such a level of radiation are prohibitive and would greatly increase the possibility of generating localised BC interference, acknowledging advancing technology even achieving a 30 db signal to noise ratio would result in a 1 or 2 watt spurious emission at power levels required to achieve 10dBW . From observation, 2 watts in ground wave range is a substantial signal at 30 miles .. Tx bandwidthIf such a increase is to be at the loss of transmitter bandwidth, this would effectively prevent the investigation of existing and the future deployment of developing digital modes. I am aware that there are stations involved in the construction of linear drive translation systems and the provision of complimentary amplification. such developments are also noted out side the Uk and would disadvantage the Uk operations. Limitations at this sage could be viewed as a retrograde step and prevent the use of a large percentage of the newer digital modes, some of which are perhaps 'too' wide even for deployment at HF but as part of a experiment may provide useful comparisons I think it reasonable with the currant power levels that the possibility of interference to existing services by excessive bandwidth is extremely low not withstanding a 'mal' adjusted system. For example I have run simple transmission test with two or three modes simultaneously, which proved of general interest inside and out of the uk and gave the observing stations a basic head to head. I am sure such tests by other stations would be useful in the future but may be prohibited by a change to the licence. Propagation investigationAs can now be observed, the K1JT narrow bandwidth auto beacon system is producing valid results from uk based stations able to transmit the system with low power into modest antenna arrays and as such is providing data over path lengths of 4000 miles. The system has limitations in terms of transmitter duty cycle however it is under development future systems may also provide data by the processing of the recovered audio. In summeryI would say the uniqueness of the UK experimental allocation should be maintained as long as possible and if necessary at the expenses of increased ERP levels which could be used to erode the facility by the 'prevention' of interference to existing services, which as far as I am aware has not been a issue to date ? Notably there exists an allocation out side of the UK of higher power than the Uk but with a quite constrictive limitation on the class of emission, the level of activity is telling. Graham . G0NBD -------------------------------------------------- From: "John W Gould" <[email protected]> Sent: Friday, December 19, 2008 4:18 PM To: <[email protected]> Subject: LF: Extension of the UK's 500kHz NoVs The annual discussion with Ofcom surrounding the extension of the NoVs for 500kHz took place at the Ofcom/RSGB Forum yesterday. This followed arequest at the September Forum meeting and was backed up with a short paperissued to them at the end November.Apart from requesting a further year's continuation of the NoV I have asked if it will be possible to increase the ERP to +10dBW in order to bring it inline with licence conditions in some other countries.Ofcom will obviously need to consult with the Maritime and Coastguard Agency (MCA) and were asking questions about the coverage at this higher ERP level.They were also asking whether we would accept a tighter definition on transmit bandwidth. This is to be more assured of not causing problems to services within the Maritime Mobile band 505 - 510kHz and I guess for the NoVs to be more compliant with the Radio Regulations footnotes 5.82A and 5.82B for 495 - 505kHz. Getting a higher ERP limit will not necessarily be to everyone's liking,however, it may help investigation of the deep fades and also help those inhigh noise level environments. The ERP level and transmit bandwidth willprobably be negotiable, but my aim is to achieve maximum flexibility in useof telegraphy and the narrower digimodes. Would 200Hz be sufficient or would we need a little more? Assuming that MCA approve of continuing the arrangements Ofcom indicated that their preference for extending the NoV would be as last year. This isto issue new NoVs to existing holders, anyone who no longer needs their NoVcan return the documents. Comments appreciated, either direct of on the reflector. Seasonal Greetings to all 73 John, G3WKL RSGB HF Manager [email protected] No virus found in this incoming message. Checked by AVG - http://www.avg.comVersion: 8.0.176 / Virus Database: 270.9.19/1857 - Release Date: 12/19/2008 10:09 |
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