INDEPENDENCE campaigners will unveil a hi-tech weapon in the battle for referendum votes at the SNP's conference starting today in Perth.

Yes Scotland believe a new mobile phone app - dubbed Yesmo - will give them the edge as the campaign enters its final months.

The software will allow door-knocking activists to refer voters' questions and concerns straight back to Yes Scotland's HQ - which will "micro-target" them with specially tailored campaign material later the same day. The app, whose name is short for 'Yes mobilisation', is based on the latest US campaigning tools but has never been used in Scotland before.

It will be officially unveiled as delegates gather for the last full SNP conference before the referendum on September 18 next year.

First Minister Alex Salmond is due to address the gathering three times, including a keynote speech on Saturday, as the party seeks to fire up grassroots supporters for the campaign.

Activists will be introduced to the Yesmo gadget at a Yes Scotland training session tomorrow.

Stewart Kirkpatrick, the cross-party campaign group's head of digital, said: "Yesmo enables us to make a rapid analysis of the data gathered by our activists on the ground.

"It is about rapid response analysis and micro-targeting."

Canvassers will use the app as they step up efforts to woo the key group of undecided voters who make up nearly a third of the electorate according to the most recent poll. In door-to-door surveys and phone polling Yes Scotland activists have already sought to place hundreds of thousands of voters on a zero-to-10 scale indicating the strength of their support for independence.

The new app comes as the SNP prepare to focus totally on the referendum under the slogan "Forward".

A series of motions - on issues including the bedroom tax and Royal Mail sell-off - have been tabled to highlight the key conference theme that Holyrood, rather than Westminster, makes the "best decisions for Scotland".

The argument will be put forward in speeches by Deputy First Minister Nicola Sturgeon and Finance Secretary John Swinney tomorrow, before Mr Salmond makes his keynote address to 1200 party members on Saturday.

The conference will close with a Yes Scotland rally, which will also hear from the First Minister and campaign chief Blair Jenkins, on Sunday afternoon.

In another bid to reach out to undecided and "soft No" voters, the SNP will also highlight the pro-UK campaign's position that an independent Scotland would be viable.

Speaking ahead of party's 79th annual gathering, SNP business convener Derek Mackay said: "The SNP are in great heart, and looking forward to a fantastic conference.

"After over six years in government, our support is still at similar levels as the 2011 Scottish Parliament election landslide - and we look forward to winning the positive case for Yes and independence."

He added: "Westminster's bedroom tax debacle is a graphic illustration of the Yes case that the best government decisions for Scotland are those made in Scotland.

"The incompetence and cruelty of the bedroom tax - and the soaring number of people dependent on food banks in resource-rich Scotland - show why we cannot afford to leave powers over welfare, the economy and pensions in Westminster's hands, and why we need to take these decisions in our own parliament."